The Compton scientific mission in Brazil in 1941: a perspective from national newspapers and documents of the time

A missão científica Compton no Brasil em 1941: uma perspectiva a partir de jornais locais da época e documentos de arquivo

Abstracts

Starting from the perspective of reports published in Brazilian newspapers at the time, as well as letters exchanged between scientists who worked in Brazil and North American colleagues, and documents from the symposium on cosmic rays, a chronological sequence of how the so-called Compton mission in Brazil took place and was perceived by the literate public will be presented. For a better understanding of the article, research on cosmic rays in Brazil and around the world is contextualized and the reasons for the creation of the mission and its coming to Brazil are discussed.

Keywords:
Compton Mission; Cosmic Rays; Cosmic Rays Symposium in Rio de Janeiro; History of Physics

Partindo da perspectiva de reportagens publicadas em jornais brasileiros da época, bem como de cartas trocadas entre cientistas que trabalhavam no Brasil e colegas norte-americanos, e documentos do simpósio sobre raios cósmicos, traça-se uma sequência cronológica de como ocorreu a chamada missão Compton no Brasil e como foi percebida pelo público alfabetizado. Para uma melhor compreensão do artigo, contextualizam-se as pesquisas em raios cósmicos no Brasil e no mundo e discutem-se os motivos da criação da missão e de sua vinda para o Brasil.

Palavras-chave:
Missão Compton; Raios Cósmicos; Simpósio de Raios Cósmicos do Rio de Janeiro; História da Física

1. Introduction

The subject of this paper is the Compton Mission¹ in Brazil, in 1941, and its scope is similar to that of a publication concerning Enrico Fermi’s visit to the same country, in 1934 [¹, ², ³, ⁴], namely: to present a historical reconstruction of how a prominent physicist spent his time in scientific and social activities during a short visit, mainly from journalistic articles released in Brazil at that time. This approach has the appeal of leading to the perception of how the fact was seen from a political and social point of view. For this accomplishment, the archives of the main local newspapers of the time reporting this Compton’s trip were investigated.

Before moving on to the central theme of this contribution, it is important to highlight the prominent role that Cosmic Ray Physics had on the first steps of physical research in Brazil, over a period of 25 years. The moments that deserve to be emphasized are: the creation of the University of São Paulo² [⁵], in 1934, the Compton Mission, in 1941; the pion discovery by the Bristol Group [⁶, ⁷], with the participation of young Brazilian physicist Cesar Lattes, in 1947; the work of Lattes with Eugene Gardner, in the newly built synchrocyclotron at the University of California, where artificially produced pions were detected for the first time, giving rise to what is called Accelerator Physics; the creation of the Brazilian Center for Physical Research (CBPF), in 1949; and finally the institutionalization of Physics in the country, which still took some time to become effective.

The barren Brazilian educational and scientific scenario in 1934 was synthetically expressed by Roberto Salmeron in this way [⁸]:

There was no specialized school in the country for the study of natural sciences, humanities or literature. People were interested in mathematics, physics, or chemistry in general when they studied engineering; those interested in biology studied medicine; literature experts came mainly from law schools, and so on. Scientists in almost all fields of science, philosophers and writers acquired most of their professional education as self-taught. Very few had the opportunity to improve their education in Europe.

This was the situation in Brazil when the University of São Paulo was founded in 1934. The existing higher schools in the city were brought together with common administration, but more important than the joining of schools from an administrative point of view was the creation of the Faculty of Philosophy, Sciences and Letters at USP,the first founded in the country. This Faculty had a huge impact on the development of science in São Paulo, with subsequent influence on other universities that were founded later. Due to this influence, the founding of the University of São Paulo was the most important event in the history of Brazilian universities.

Concerning the foundation of this Faculty, with emphasis on the participation of Italian scientists, including Wataghin, see his granddaughter’s testimony in Ref. [⁹].

Regarding Physics, one can safely affirm that this situation begins to change with the arrival in São Paulo of the Italo-Ukrainian physicist Gleb Vassielievich Wataghin [⁸, ⁹, ¹⁰, ¹¹, ¹², ¹³] appointed by Fermi [³], who preferred to remain in Europe. There, Wataghin worked in both theoretical and experimental physics, having created an important experimental research group on Cosmic Ray Physics. He is considered the father of physical research in Brazil. The reasons are many. First, for having introduced knowledge and teaching about Relativity and Quantum Physics at USP. Second, for having had a fundamental contribution to the establishment of systematic research in Physics in the country, starting in the 1930s, which until then was restricted to isolated cases and without any institutional support.

The initial experimental research, coordinated by Wataghin, was on the multiple production of mesons and involved young scientists such as Marcello Damy de Souza Santos,³ who was a student in the first class that Wataghin taught in Brazil, and the first, in 1938, to get his degree in Physics, from Faculty of Philosophy, Sciences and Letters at USP. Then came Paulus Aulus Pompéia [¹⁴],⁴ who became Wataghin’s assistant, Oscar Sala [¹⁵],⁵ Yolande Monteux.⁶ Later, others joined the group, such as the Italian physicist Giuseppe Occhialini [¹⁶, ¹⁷], who came from Italy invited by Wataghin to work at USP, from 1937 to 1944, and Cesar Lattes⁷ [¹⁸, ¹⁹].

In 1940, Pompéia, Damy and Wataghin carried out an experiment in São Paulo that detected unexpected events:⁸ showers of particles that could pass through tens of centimeters of lead [²⁰, ²¹, ²²]. At that time, electromagnetic showers were known, but these could be stopped by a few centimeters of lead. The detected showers, which crossed tens of centimeters, could therefore not be electromagnetic. They were of a new type, which the authors called penetrating showers. They are what we today call hadronic showers, groups of hadrons produced together in strong interactions. Hadronic showers are one of the most important elements in high-energy collisions. All large particle detectors used in high-energy experiments must have hadronic shower detectors. The importance of this discovery was soon recognized by Heisenberg [²³].

Roberto Salmeron maintains that the experimental work of Pompéia, Damy and Wataghin was a significant stimulus for carrying out another important experiment [⁸], which culminated in the discovery of the V particles [²⁴], later called strange particles, which revolutionized Particle Physics. Indeed, in his opinion,

Patrick Blackett, one of the most eminent physicists specializing in cosmic rays, director of the Department of Physics at the University of Manchester, in England, influenced by the São Paulo experiment, after the Second World War suggested to G. Rochester and C. Butler that carried out an experiment on penetrating showers, using a Wilson chamber immersed in a magnetic field as a detector. The experiment was carried out, and discovered a new type of particles, then unknown, which were called “V particles”, because they disintegrated into two other particles whose traces form a V in the Wilson chamber.

Once detected, in cosmic rays, the cascade hadronic production containing several particles (including mesons) with very high energies, which reach the Earth with great penetrating power, naturally posed the question whether many particles could be produced simultaneously in a single collision, or if only a single particle would be produced in each collision and the cascade of particles would be the result of several successive collisions. The first mechanism, i.e., many mesons produced together, is called “multiple production”, and was defended by Heisenberg and Wataghin. The second one, by which a single meson would be produced in a collision and the shower would be the result of many successive collisions, was called “plural production”, and its most prominent supporter was Walter Heinrich Heitler. We now know that the multiple production hypothesis is correct. Therefore, Wataghin, Souza Santos and Pompéia are internationally recognized as the discoverers of the multiple production of mesons in penetrating showers, through the works published in the Physical Review, in 1940.

Wataghin’s Cosmic Ray group was scientifically motivated by Compton’s visit, although one cannot asseverate that it was free of political connotation and professional interests. In practice, there was a significant participation of Wataghin’s group at the Cosmic Rays Symposium organized as part of the Compton Mission. Indeed, one can anticipate that two thirds (14/21) of the Communications were presented by Brazilian scientist or foreigners who had settled in the country. This Symposium was probably the first international physics meeting held in in Brazil.

In organizing the Compton Mission, which involved the United States, Brazil and Bolivia, São Paulo counted on financial assistance from the Rockefeller Foundation, at Compton’s suggestion, which began giving money for research to be carried out at the USP Physics Institute. Furthermore, there was, according to Wataghin himself [¹²], “a generous and immediate contribution” made by Adhemar de Barros, who was just an intervenor in SP in the period 1938–1941 [¹⁵].⁹

To be honest, it is not possible to separate Cosmic Ray Physics from Brazilian scientific policy and how it fits into a larger context of foreign relations during the period when Physics flourished in Brazil, between 1930-1950, and even afterwards, if one consider the beginning of scientific research institutionalization in the country, as shown in the references [²⁵, ²⁶]. It is in such broad scenario that the Compton Mission is inserted, although to achieve it, it must be remembered that a real diplomatic battle was about to be fought, due to WWII [²⁷, ²⁸].

However, no one in their right mind would believe in the power of a scientific expedition to convince Brazil to enter the war on the side of the allies. An essential point for President Getulio Vargas was his project for a national steel industry to boost the country’s development. He envisaged the construction of a steel plant that could supply steel to his allies during the Second World War and, in peace, help with the development of Brazil. In fact, since 1939, the Vargas government maintained negotiation missions, both in the United States and England, and in Nazi Germany, in search of financing possibilities for its steel project. In the midst of the Second World War, the Brazilian position was in the interest of the Allied countries (France, England, USA and, later, the USSR) but also of the Axis countries (Germany, Italy and Japan) and Getulio Vargas played with this.

As Lira Neto highlights, in his biography of Getulio [²⁹], p. 385, there was an obstacle to Getulio’s dream:

For Getulio, the big obstacle was that Brazil could not wait for the end of the war to only then begin transactions with Germany – or with any other world power. The country’s greatest asset came precisely from the existence of the war. In normal times of peace, Brazil would not have a privileged negotiation space or arguments solid enough to prevail before the most powerful nations. The moment of exceptionality, in which the country’s geographical position was being treated as strong currency, gave [to the Palácio do] Catete a decisive bargaining power: exchanging the promise of alignment for the steel industry.

In June 1940, the Brazilian president made a controversial speech on board the battleship Minas Gerais, which was interpreted as announcing Brazil’s accession to the Axis countries. The Nazis immediately authorized Ambassador Curt Prüfer to request an audience with Getulio, to offer him proposals they considered tempting for economic cooperation, in exchange for Brazil’s alignment with the axis [²⁹], p. 384. An important and perhaps decisive obstacle was that Germany’s proposals, specifically, were for after the War. Faced with the risk highlighted, the USA was forced to release the loan through the Export-Import Bank of the United States (Eximbank), in exchange for Brazilian alignment with its positions.¹⁰

Thus, Companhia Siderúrgica Nacional (CSN) was created by decree during the Estado Novo, following a diplomatic agreement called the Washington Accords, made between the Brazilian and American governments. More precisely, President Getulio Vargas signed, on April 9, 1941, the decree for the creation of the CSN, about 2 months before the Compton Mission.

2. Prelude to Cosmic Ray Research Prior to Compton’s Expedition to Brazil

2.1. The genesis of cosmic ray exploration

In the dawn of the 20th century, Charles Thomson Rees Wilson, a Scottish physicist, embarked on a series of experiments using a gold leaf electroscope. His observations unveiled persistent air conductivity that could not be explained by the known radioactivity of the earth’s crust, hinting at the influence of a deeply penetrating radiation. Wilson, who later shared the 1927 Nobel Prize with Arthur Compton for his method of visualizing the trajectories of charged particles with his cloud chamber, postulated, in 1901, that this enduring ionization could be attributed to radiation emanating from beyond our planet’s atmosphere. This enigma spurred a multitude of hypotheses, ultimately leading to the pivotal experiments of Austrian physicist Victor Franz Hess. In 1912, through his atmospheric balloon ascents, Hess (Figure 2) verified the presence of ionizing radiation originating from outer space, thereby earning recognition as the founding father of cosmic rays physics [³⁰].

Figure 1
One day of Compton Mission in Bauru (SP), where young Oscar Sala went as a spectator. Standing, in the center, Arthur Compton; the first one on the right is Oscar Sala. Source: IFUSP Collection.

Figure 2
Victor Hess in his balloon before the flight sometime between 1911 and 1912 [³⁹].

The advent of the 20th century heralded the genesis of cosmic ray research, a domain poised to demystify some of the cosmos’ most elusive secrets. This era was marked by innovative experimental endeavors, theoretical advancements, and the advent of novel technologies that significantly enhanced our comprehension of these mysterious particles. Hess’s contributions for the field of cosmic ray research, culminating in his Nobel Prize in Physics in 1936, is a milestone for an important new chapter in Physics research [³¹, ³², ³³, ³⁴, ³⁵, ³⁶].

From the point of view of Brazil, theoretical studies on cosmic rays had already been introduced in the country, in 1933, by German physicist Bernhard Gross [³⁷]. Gross’s interest was related to ionization process caused by cosmic radiation and its interaction with matter. He had started these studies in Europe, before emigrating to Brazil to establish himself in Rio de Janeiro [³⁸].

Another appealing reason, in a historical perspective, to be interested in cosmic ray is that some investigations in this area suggested that it could emerge as a field of knowledge quite promising, as it actually happened, involving the discovery of new particles – like the positron, muon and pion – as well as new aspects of Astronomy and Cosmology. Furthermore, its relatively low cost at the beginning would enable the introduction of experimental research projects in Brazil, where it would have been unfeasible at that time to implement facilities for create a High Energy Physics laboratory.

2.2. Progress in detection methods andtheoretical frameworks

As seen in the previous section, the first studies of cosmic rays are forever associated with balloons. Despite the development of new techniques and new electronic devices, cosmic ray research has not abandoned the support of balloons, as it was indeed the case with the Compton mission, in 1941.

Photography left a mark of incomparable importance in Modern Physics and, in particular, was essential in paving a new path for research into cosmic rays. One sought to apply it generically to the detection of nuclear radiation since the discovery of natural radioactivity and especially after the enormous success of X-rays allowing us to “see” what was previously invisible. However, it was necessary to wait for the year 1937, when two women, Austrian physicists Marietta Blau and Hertha Wambacher, published a photographic reproduction of a nuclear event, originally recorded in nuclear emulsions exposed to cosmic radiation at mountain altitude.

At first, the idea was just to take photographs as a way of visually recording the event. In a second stage, photographic films were improved, allowing a different record of events, with the well-known technique of photographic emulsions. Now, the records in the emulsions could be scrutinized with the help of microscopes, allowing measurements to be taken using these records on emulsion plates. Details of this “new world of emulsions” are given in Ref. [⁴⁰].

Also the invention of the Geiger-Müller counter, in the 1920s, represented a big leap in the precision of cosmic ray measurement. Theoretical physicists, including the illustrious Arthur Compton, delved into the cosmic ray implications for deciphering the universe’s constitution.

The 1930s witnessed a surge of activity in the realm of cosmic ray research, with notable contributions such as Giuseppe Occhialini at the Cavendish Laboratory [¹⁶]. Occhialini had experience with Wilson chambers, which he had acquired from Patrick Maynard Stuart Blackett. The Wilson chamber, also known as the cloud chamber, is an instrument capable of identifying elementary particles and played an important role in the study of cosmic rays. It was with one of these chambers that the American physicist Carl David Wilson discovered the first antiparticle: the anti-electron or positron, a significant scientific breakthrough.

In 1937, Occhialini came to Brazil, fleeing fascism in Italy, where, together with Wataghin, began the first research activities in Physics in Brazil, forming the first group of students at the Faculty of Philosophy and Letters, where he founded the Department of Physics, the current IF/USP.

2.3. The Millikan-Compton latitude effectcontroversy

Among the most captivating episodes in cosmic ray research history is the debate between Robert Millikan and Arthur Compton regarding the latitude effect’s influence on cosmic ray intensity. A good summary on this subject, geomagnetic and meteorological effects on cosmic rays can be found in an article by Alfredo Marques [⁴¹]. This debate not only steered the direction of cosmic ray studies but also underscored the essence of scientific dialogue [⁴², ⁴³].

Robert Millikan, a Nobel laureate celebrated for quantifying the electron’s charge, shifted his focus to cosmic rays in the 1920s. Convinced that cosmic rays were photons – quanta of light from the cosmos rather than charged particles – Millikan coined the term ‘cosmic rays’ and embarked on extensive research to substantiate his theory.

Arthur Compton, distinguished by his Nobel Prize-winning research on X-ray scattering, advocated a contrary perspective. Compton’s investigations suggested that cosmic rays were indeed charged particles, implying that their intensity would be modulated by the Earth’s magnetic field, an effect expected to vary with latitude [⁴⁴].

The latitude effect denotes the phenomenon where cosmic ray intensity is contingent upon the geographic latitude of measurement. This effect arises from the Earth’s magnetic field, which more effectively deflects charged particles at higher latitudes near the poles, where the field is more potent, and less so at equatorial latitudes.

The Millikan-Compton dispute escalated into a public and fervent defense of their respective stances, backed by experimental evidence and scholarly publications. Millikan’s experiments appeared to negate any significant latitude effect, bolstering his argument against the existence of charged cosmic particles. Conversely, Compton orchestrated a series of global balloon expeditions, including those inserted in 1941 Compton mission, amassing data that unequivocally demonstrated the latitude effect, thereby reinforcing the notion that cosmic rays are charged particles.

The debate ultimately tipped in favor of Compton’s hypothesis as subsequent experiments validated the latitude effect, affirming the charged nature of cosmic rays. This revelation had far-reaching implications for cosmic ray study and particle physics comprehension. The Millikan-Compton debate is commemorated as a seminal event in the annals of science, epitomizing the critical role of meticulous experimentation and candid discourse in the pursuit of knowledge.

2.4. The influence of the World War II

The World War II had a significant impact on the field of cosmic ray research, both directly and indirectly. During the war, many physicists were recruited for military efforts, which led to a temporary slowdown in cosmic ray research. However, the war also spurred technological advancements that would later be instrumental in the study of cosmic rays.

The development of radar technology during the war, for example, was a critical innovation. Initially used for military purposes, radar technology later became a valuable tool for detecting and studying cosmic noise and radio emissions from the sun and other celestial bodies. This and others technological achievements of the war effort designed a new horizon for cosmic ray research, as scientists began to explore the universe not just through visual observations but also through electronics and radio astronomy.

Moreover, the wartime claim to better communication and detection systems led to improvements in electronics and instrumentation. These advancements were beneficial for post-war physical research in general and for cosmic ray in particular, as they allowed for more precise measurements and detection of cosmic rays.

In the Soviet Union, cosmic ray research continued to progress during the war, with studies indicating that cosmic radiation might have an effect on the earth’s atmosphere and possibly even influence the weather [⁴⁵]. This suggests that despite the challenges posed by the war, scientific inquiry into cosmic rays persisted, and in some cases, even thrived.

3. The Scientific Motivation

3.1. Compton scientific profile in a nutshell

Born in 1892, the American physicist Arthur Holly Compton earned his Ph.D. from Princeton University, in 1916. Following a year as a physics instructor at the University of Minnesota, he transitioned to a role as a research engineer at the Westinghouse Lamp Company, in Pittsburgh. Subsequently, more precisely in 1919, he embarked on a journey to the University of Cambridge, assuming the role of a National Research Council Fellow.

In 1920, Compton moved to Washington University in St. Louis, ascending to the position of the head of the physics department. Three years later, in 1923, he furthered his academic journey at the University of Chicago, where he worked as a physics professor for the next 22 years, returning to St. Louis as chancellor in 1945 and, from 1954 until his retirement in 1961, he served as a professor at the University of Washington.

The culmination reward for his groundbreaking work came in 1927, when Compton divided the Nobel Prize in Physics with C. T. R. Wilson.¹¹ This prestigious award honored his discovery of the increase in the wavelength of X-rays when they are scattered by free electrons. This revelation led to the understanding that the scattered quanta possess less energy than those of the original beam, a phenomenon now universally recognized as the Compton effect [⁴⁶, ⁴⁷, ⁴⁸], which was essential for the corpuscular nature of light to be better accepted by the community of physicists.

Since the late 1920s, Compton has already joined experiments on cosmic rays in the Kashmir mountains in India and, in 1930, he had set up an experimental program with the intention to study cosmic rays at high elevations such as found in South America, confirming the observations (1927) by Jacob Clay, on voyages between Holland and Java, of the influence of latitude on cosmic ray intensity. It is important to highlight that such experiments in South America were not new at the time, since they had been carried out by the Nobel Prize winner and former Compton professor, Robert Andrews Millikan, since the beginning of the 1920s. The studies carried out by Compton ended up creating a controversy with Millikan about the nature of cosmic rays since his results differed from previous results obtained by Millikan [⁴²], as briefly discussed in Section ^2.3.

3.2. Compton’s interest in South America

Compton regularly participated in several international Cosmic Ray symposia. He was aware of the controversy over the production of “heavy electrons” (initially called mesotrons and later mesons): would it be “multiple”, from a single collision between the cosmic rays and the atmosphere, or “plural”, as Werner Heisenberg had suggested in 1936-37 [⁴⁹, ⁵⁰]? The first alternative was confirmed by an experiment done by Wataghin, Souza Santos and Pompeia at the Faculty of Philosophy. Sciences and Letters of the São Paulo University, with the help of Brazilian Air Force (FAB) planes went up to a height of 7 km, published, in 1940, in Physical Review [⁵¹].

Wataghin had been informed in a letter sent by Pompeia, in December 1940, of Compton’s intentions to pass through Brazil on his expedition [⁵²]. In a letter (Figure 3) dated January 4, 1941, Compton thanks Wataghin for sending him the manuscript of his article and confirms his intention to carry out new cosmic ray experiments in South America, more specifically in Bolivia, Peru and following the suggestion by Paulus Aulus Pompeia, also included, in Brazil, the state of São Paulo in his experiences. In this same letter, Compton invites Wataghin to collaborate in his research [⁵³]:

We know that you are considering also carrying out experiments on cosmic rays in the mountains. We should be very happy if it is possible to cooperate in some or all the experiments that we have just outlined. it would be especially pleasant if you can have an expedition in the Andes that could work together with ours while we are there in June and July, or if sone one from your laboratory could collaborate with us in the balloon experiments in southern Brazil. I invited Pompeia to go with us on this expedition, but he does not find it practicable at this time.

We shall keep you advised from time to time as our plans progress.

Figure 3
Letter from Compton to Wataghin confirming the intention to carry out new cosmic ray experiments in South America [⁵²].

Compton led the expedition, strategically selecting various regions in Brazil, Peru, and Bolivia due to their proximity to the magnetic equator [⁵⁴]. The intensity of the magnetic field tends to decrease from the poles to the magnetic equator. In addition, South America has a region known for the effect of the South Atlantic Anomaly (SAA) that leads to an even greater flow of energetic particles in this region [⁵⁵, ⁵⁶]. In Brazil, 21 hydrogen-filled specialized balloons, equipped with measuring instruments, were released form the cities of Bauru and Marília, both in the interior of São Paulo, reaching altitudes of at least 25 kilometers. Meanwhile, in Peru, a series of experiments were conducted to capture photographic trajectories and measure the intensity of cosmic rays. This collaborative effort marked a significant contribution to the understanding of cosmic rays and their behavior in the unique geographical settings of South America during a pivotal period in history.

Professor William Polk Jesse together with Pompéia, from the University of São Paulo, will be responsible for the research in Brazil. In Peru, Dr. Ernesto O. Wolan and Dr. Donald J. Hughes were responsible for photographing cosmic rays in San Cristobal near Lima. Dr. Norman Hilberry and his wife Dr. Ann Hepburn Hilberry, both from New York University, were responsible for the cosmic ray measurements [⁵⁷, ⁵⁸, ⁵⁹].

Wataghin, together with the president of the Brazilian Academy of Sciences Arthur Moses, motivated by the trip that Compton would already take to Brazil organized an International Symposium on Cosmic Rays which took place in Rio de Janeiro, at the end of Compton’s visit. In addition to Compton, Wataghin expressed in a letter to Moses the intention of inviting physicists like Enrico Fermi, Hans Bethe, Bruno Rossi and Wolfgang Pauli to the symposium [⁶⁰].

In a further letter written by Compton to Wataghin, on April 21, 1941, already aware of the symposium, Compton requests that it take place between the 4th and 6th of August [⁶¹]:

Mr. Pompeia has told us of your plans with regards to a symposium at Rio de Janeiro. It would be most convenient for us if this could be held from August 4 to 6. This would let us complete the work in Peru in time for the men there to come to Rio for the conference. Immediately afterwards most of us would return to the United States.

However, Compton’s arrival in Brazil was not only motivated by findings published by Brazilian scientists; it also occurs amidst a geopolitical backdrop where the United States sought alignment with different South American countries in support of the Allied forces during World War II [²⁷]. About a month after Compton’s arrival, Walt Disney visited Rio de Janeiro, more specifically between August 17th and September 8th, with the same objective of gaining sympathy from Brazilians towards North Americans. In the capital, he participated in the launch of the feature film Fantasia (1940) and, impressed by the reception, he created the character Zé Carioca, with the pretext of finding companions for Donald Duck and Goofy.

The International Symposium took place at Rio de Janeiro between August 4 and 8, 1941, and its proceedings were published two years later [⁶²] by the Academia Brasileira de Ciências.

4. The Compton Mission

4.1. Warnings concerning the press news

Here, initially, some warnings regarding the journalistic publications consulted should be given.

Arthur Compton, winner of the 1927 Nobel Prize in Physics, was a well known scientist among the community of physicist, but certainly became much more known to general public after having his photo printed in the cover of Time Magazine for January 13, 1936 (Figure 4), including people from Brazilian press.

Figure 4
Photo of Arthur H. Compton on the cover of Time Magazine for January 13, 1936 [⁶³].

This was the fifth Time issue with a scientist on the cover since 1928. This fact probably facilitated the choices of so many newspapers to publicize his stay in Brazil. Furthermore, balloons, to this day, are part of a positive collective imagination, exerting a certain fascination on the reading public.

Mostly, the reports were not on the front pages of the newspapers; however, in some cases, a small headline about the mission was found on the first page, directing readers to the complete and more detailed text on a subsequent page. Out of the 127 articles used in this research, only 9 were featured with some prominence on the front page of the newspapers [⁵⁴, ⁵⁹, ⁶⁴, ⁶⁵, ⁶⁶, ⁶⁷, ⁶⁸, ⁶⁹, ⁷⁰]. Statements and comments from Brazilian scientists were not found in the newspapers.

The last observation here concerns readers of this type of news. No statistical study concerning a feedback of whether the news were read or not by the general public was found. However, it is well known that the print media has always had its own mechanisms for verifying the reach of its news. The very fact that so many newspapers were involved in reporting on the Compton Mission suggests that they considered the return at least satisfactory.

But one can go further and argue that this experience, added to the previous ones with the visit of Einstein and Fermi to Brazil, considering in addition the distinct role of science in the victory of the WWII, and the subsequent enormous success of Lattes’ discovery in the Brazilian press, may have been decisive for a unique initiative in the country: the creation of Ciência para Todos, a twelve-page science supplement published on the last Sunday of the month, for five years (1948-1953), included in the “carioca” newspaper A Manhã [⁷¹]. It is worth remembering that issue no. 1 features a full-page article by José Leite Lopes [⁷²], with the following title: New Horizons for Atomic Physics – the importance of the works of the Brazilian scientist Cesar Lattes [⁷³].¹²

4.2. Comments on diplomatic/scientific mission

Every diplomatic mission, including scientific ones, has a strong political component. This was particularly true in the case of Compton Mission due to the war time. This subject was extensively covered in the article [²⁷]. In any case, it is worth to make the following comment.

During a time when the Vargas government was still engaged in political maneuvering to determine which support would bring the greatest benefit to the country at the end of World War II, the United States, through the Office of the Coordinator of Inter-American Affairs (OCIAA), implemented several measures aimed at aligning Brazil with its interests. With these goals in mind, the Compton mission was at its core politically and financially supported by the OCIAA. However, it was not only this support that defined the mission; the strong anti-fascist sentiment among São Paulo physicists of the time also ensured that the mission was in the interest of all parties involved. Nevertheless, despite significant press adherence, including Compton’s presence in the “Hora do Brasil” programming managed by the DIP,¹³ there is no evidence that the mission was exploited by Vargas for personal or political gain.¹⁴

4.3. Reconstruction of the activities of theinvolved scientists

On June 18, 1941, the electrical engineer with a degree in physical science Paulus Pompéia was the first member of the Compton mission arrived in Rio de Janeiro aboard the transatlantic Argentina. Pompéia attended, during the period from 1940 to 1942, to improvement course at the Compton laboratory in Chicago.¹⁵ And, together with Gleb Wataghin, carried out preliminary experiments on the arrival of the Compton mission in Brazil [⁷⁴].

On the July 16th, from the municipality of Jaú, located in the central region of the state of São Paulo, the meteorology service of the Ministry of Agriculture in Rio de Janeiro, under the leadership of meteorologist José Carlos Junqueira Schmidt, conducted the first set of a series of aerological soundings. The objective was to facilitate the future retrieval of instruments designated for experiments carried out by the Compton mission. Aimed to determine the optimal location for the official launch of the instrument. In this initial sounding, the balloons landed near the city of Bragança, located 221 km southeast of Jaú [⁷⁵, ⁷⁶, ⁷⁷]. On the same day, Jesse, aboard the ship Uruguay, passed through Rio de Janeiro and departed the following day for Santos, [⁷⁸, ⁷⁹, ⁸⁰]. On board the ship, Jesse was interviewed by the newspaper O Globo [⁶⁹], when he clearly defined the goal and the strategy of the mission, declaring:¹⁶

Cosmic rays come from regions beyond our planetary system. Upon reaching the great heights of the Earth’s atmosphere, they form very interesting particles called “mesotrons”, which are characterized by their great penetrating power. In the depths of the mines, “mesotrons”¹⁷ have been measured that cross 400 meters of solid rock.

The objective of our expedition is to determine the number of “mesotrons” formed in the high atmospheric regions here in Brazil, close to the earth’s magnetic equator, compared with the number already found in Chicago.

For this purpose, a measuring device of “mesotrons” is dragged by 15 to 20 balloons loaded with hydrogen. At a height of 25 kilometers some of these balloons burst and the device slowly falls to earth supported by the other balloons that remain intact. When the Device is retrieved, a photographic film reveals the altitude reached, the temperature and the intensity of the “mesotrons” during the entire flight, which lasts approximately eight hours and covers approximately 150 kilometers.

On July 18th and 21st, Schmidt, continuing his sounding efforts, launched two additional sets of balloons that reached the city of Pouso Alegre, in the state of Minas Gerais. Pouso Alegre is located 271 km east of Jaú, and the second wave of balloons landed in the vicinity of the municipality of Itapira, approximately 180 km east of Jaú. As a result of these soundings, the city of Bauru, located 50 km west of Jaú, was chosen as the most favorable location to proceed with the experiments [⁷⁶, ⁸¹].

On the July 27th, Compton arrived in São Paulo where he was received by few members of the Brazilian Academy of Sciences: Alvaro Alberto da Mota e Silva, Joaquim da Costa Ribeiro, Guilherme Florence, and Francisco Emygdio da Fonseca Telles and then was taken to the Hotel Esplanada [⁸², ⁸³, ⁸⁴].¹⁸

Between the 28th and 31st of July, devices designed to record cosmic radiation, shown in Figures 5, 6 and 7, were launched in hydrogen balloons at altitudes of up to 20 or 30 km into the stratosphere. According to a statement by Wataghin himself, reproduced in Ref. [¹⁹], they could reach heights of 35 or 40 km.

Figure 5
Arthur H. Compton, outdoors, next to a specific device a moment before the launch of the balloons was about to begin [⁷⁵].

Figure 6
On the left we have a general view of the device used to record the cosmic radiation (A) amplifying tubes, (c) counters and (R) recorder; on the right, we have a more detailed view of the recording instrument, with: (B) barometer element, (C) driving clockwork, (D) drum and (M) microscope [⁶²].

Figure 7
Compton checking out a device, a routine before the launch of the sounding balloons [⁷⁵].

Using the data obtained in the test launches from the 16th to the 21st of July, four cities in the state of São Paulo were chosen for the official launch: São Pedro de Piracicaba, Jaú, Baurú, and Marília. In total, 11 groups of devices were launched, dragged by hydrogen balloons, Figures 8, 9 and 10 [⁶⁵].

Figure 8
Preparation of equipment at Bauru airport, launch site [⁶²].

Figure 9
Devices being launched dragged by hydrogen balloons [⁶²].

Figure 10
Set of 16 balloons in the sky carrying the recording devices [⁶²].

In the edition of July 31, 1941, Compton gives an interview to the Jornal A Noite [⁶⁵] detailing what the experiments are about and anticipating the expected conclusions:

The experiments consist of observations made with recording devices, which are dragged by balloons to high altitudes. Weighing approximately 10 kilos, these devices can reach heights of over 25 kilometers, where the rays coming from outside are not greatly affected by the layer of air crossed. The recent measures taken in the USA. By means of balloons and similar devices. They demonstrate that the particles that penetrate the atmosphere are composed of protons. These constitute the heavy part of hydrogen atoms containing a positive electrical charge.

If this assertion is rigorously proved in the vicinity of the magnetic equator, we will conclude that only high energy protons can reach the atmosphere and that they come more frequently from the West. Particularly interesting will be the study of energy transmission from protons to the secondary rays they produce.

For this study it will be necessary to keep the balloons in the air for many hours, therefore subject to the winds. Therefore, they can fall many tens of kilometers from the starting point. Only with the recovery of the balloons and the respective equipment, the results of the experiments can be obtained. In some cases, these balloons may be accompanied by an airplane. With the cooperation of the Brazilian government, the physics department of the same university, and the Brazilian press, the expedition hopes to be able to recover the balloons that carry a label declaring the prize and the address to which whoever finds them should go.

Messrs. Hugues and Wollan will photograph the trajectories of cosmic rays. These photographs will be obtained by means of condensing ions that are visible and photographable and that will reveal the type of particle, the energy value, and the direction in which it moves. At the accessible altitudes of Peru, types of particles rarely observed at sea level are likely to be found.

It is also hoped that with the studies of Mr. Hilberry in “El Misti”, it is possible to know how many particles there are of a certain energy produced by the cosmic rays that reach the atmosphere. Its devices, including thermionic valves and batteries, will need to be transported on donkeys through trails, to climb the peak of the mountain, at an altitude of approximately six thousand meters.

The study of cosmic radiation has become one of the most active fields of research: it is the best available method for investigating the fundamental particles that make up matter. Crystals are composed of molecules, molecules are composed of atoms, which in turn are composed of parts known as electrons, protons, and neutrons, etc.

With cosmic rays, the relationships between these various elementary particles can be studied. The previously unknown positive electron has been found in cosmic rays. The same happened with the mesotrons, which have a mass of intermediate value between the mass of the electron and that of the proton. By means of cosmic rays it is possible to study the transformation of protons into mesotrons and of these into electrons. The basic investigation of matter is scientifically as important as its study at other levels, such as the study of the distribution of atoms that form molecules and which we call chemistry. So far, its practical importance has not become evident. However, it seeks to increase the basic knowledge of the fundamental structure of matter.

On August 1st, at 9 pm, Professor Compton gave a lecture on the theme Cosmic Rays, in the main hall of the Faculty of Philosophy, Sciences and Letters, in São Paulo. For more than two hours, Compton made a complete and detailed presentation of his research in the Americas. He used photographic projections for illustrating his conference [⁸⁵, ⁸⁶, ⁸⁷].

On the 3rd of August, Compton, together with his assistants and their respective wives, arrived in Rio de Janeiro from São Paulo by the Cruzeiro do Sul¹⁹ train [⁸⁸, ⁸⁹, ⁹⁰, ⁹¹, ⁹²]. He was received at the Pedro II station by members of the Brazilian Academy of Sciences and accompanied by them to the Hotel Glória,²⁰ where they will be staying. On that day, the “Grande Prêmio Brasil” was held at the Gávea Hippodrome, where the Compton mission together with the Portuguese writer António Joaquim Tavares Ferro, known as António Ferro, was received for a lunch hosted by the journalist and politician Lourival Fontes, Director of the press and advertising department (DIP).

On the 4th of August, Compton was interviewed by the newspaper A Noite [⁹³] telling a little about his experiences in São Paulo:

The experiments carried out show not only the capacity of Brazilian scientists, but also allowed me to assess the kindness and hospitality of their country. The experiments in São Paulo were very successful.

Continuing with the interview, Compton commented a little about what he would say in his presentation.

In my communication today, I will address Alf’ven’s theory on the origin of cosmic rays and also, I will address the magnetic fields of galaxies. This theory, consider the emission of electric particles in a great mass of animated stars in spiral motion.

And at 9 am in the main hall of the National School of Engineering,²¹ Compton started the opening conference, Figure 11, of a week of debates on cosmic rays organized by the Brazilian Academy of Sciences [⁹⁴, ⁹⁵, ⁹⁶, ⁹⁷, ⁹⁸, ⁹⁹]. The minutes of the Meeting of the Cosmic Ray Seminar was published by a traditional Brazilian periodical, Jornal do Commercio, in its edition on the 16th of August, 1941 [¹⁰⁰].

Figure 11
Arthur H. Compton in the “Symposium sôbre Raios Cósmicos”, on August 4, 1941 [⁶²].

In addition to Alfvén theory,²² he also addressed issues such as measurements of magnetic fields and cosmic radiation, including the deviation of the trajectory of cosmic rays by the magnetic mass of the Earth and other celestial bodies. Then, he passed the word to one of his assistants, William Jesse, who began his communication.

On the same day, August 4, the Minister of Foreign Affairs Osvaldo Aranha hosted a lunch at the Jockey Club for members of the Compton scientific mission. Also in attendance were the US Ambassador Jefferson Caffery, the General Secretary of the Ministry of Foreign Affairs Mauricio Nabuco, the President of the Brazilian Commission on Intellectual Cooperation Miguel Osorio de Almeida, the Rector of the University of Brazil,²³ Raul Leitão da Cunha, in addition to professors Arthur Moses, Carlos Chagas, Meneses Oliva, Flexa Ribeiro and Inacio Amaral. In the afternoon, Professor Arthur Moses and his wife offered the members of the mission a reception at their residence located on Rua Muniz Barreto in Botafogo neighborhood, which was also attended by figures from the diplomatic corps of the government and society in the city of Rio de Janeiro [¹⁰¹, ¹⁰², ¹⁰³, ¹⁰⁴, ¹⁰⁵, ¹⁰⁶, ¹⁰⁷].

On the 5th of August, the newspaper O Globo reported Compton’s decision to postpone his return to the United States, which would have taken place on the 7th, to the 9th of August, at the request of the Instituto de Estudos Brasileiros so that he could participate in another conference on the 8th [¹⁰⁸].

On August 6th, after the second session of that Symposium day (Figure 12), Compton made a night visit to the studios of radio division of DIP and spoke into the microphone on a national radio program called “Hora do Brasil” [¹⁰⁹, ¹¹⁰, ¹¹¹, ¹¹², ¹¹³]. At this opportunity, he thanks the cooperation of Brazilian physicists, essential for the achievements of the Mission, and conclude urging rapprochement between Brazil and the USA in the face of the War in Europe. In his words:

Listener friends. I am pleased to greet our Brazilian friends, who treated us so cordially during our brief visit. In response to the kind invitation of the Brazilian Academy of Sciences and the physicists of São Paulo and Rio de Janeiro, a small group of scientists from the University of Chicago came to your country to study cosmic rays and discuss some of our mutual problems with Brazilian scientists.

Our experiments here have consisted of raising balloons with instruments that record cosmic rays as they approach the earth. Your meteorological service and your air service have provided us with the greatest cooperation and assistance to carry out our balloon flights. Your radio and your press have also helped us a lot, keeping the public alert in search of the instruments as they descend. Even more important has been the cordial cooperation of physicists from your universities, headed by Professor Wataghin from São Paulo. Without this help, our work in Brazil would not have been possible. But, with your cooperation, we have already managed to achieve an important part of our objectives and successfully address what is missing. Above all, we took enormous advantage of the conferences we had last week with scientists from Brazil. The development of ideas arising from discussions of this nature is the most important result of a visit such as ours. We would also like to say how much we have appreciated your most cordial hospitality and the countless courtesies with which we have been showered, officially and by personal friends. Your country, like ours, faces new responsibilities. For many centuries now, we have been turning our eyes eastwards, to the countries that preceded us, seeking there our culture and our science. Gradually the strength of our civilization grew. Brazil became the leader of Portuguese culture. The United States has developed an improved industry. Now Europe is involved in a tragic struggle.

If the torch of civilization is to continue to shine, it is our responsibility to keep it burning.

We pray, with sincere hope, that Europe will quickly return to the enjoyment of its inheritance. We want to pay you our big debt. However, it is becoming more and more necessary for your country and our country to look to each other for friendship and cultural stimulation. We would like to thank you for the frank hospitality with which you received us, who seek to work with you in a common task.

Figure 12
Participants of the 4th Meeting of “Symposium sôbre Raios Cósmicos”, on August 6, 1941. The following scientists can be identified in this photo: in the first row, from right to left, the second is Arthur Compton, then Carlos Chagas Filho, Gleb Wataghin and Ernest O. Wollan. In the second row, on the right one has Francisco Mendes de Oliveira Castro and by his side Marcello Damy de Souza Santos; the fourth in that same row is Arthur do Prado. In the last row, second from the right is Joaquim Costa Ribeiro and next to him is Bernhard Gross [⁶²].

On the 8th of August, at the National School of Engineering, the last section of the symposium was held (Figure 13) under the presidency of Compton [⁹³, ⁹⁴, ⁹⁵].

Figure 13
Final reunion of the “Symposium sôbre Raios Cósmicos”, on August 8, 1941. All those portrayed are identified: 1 - Gleb Wataghin; 2 - Donald Hughes; 3 - Norman Hilberry; 4 - Arthur Moses; 5 - Arthur H. Compton; 6 - William P. Lesse; 7 - Ernest O. Wollan; 8 - René Wurmser; 9 - Francisco Souza; 10 - F. M. de Oliveira Castro; 11 - F. Venancio Filho; 12 - J. Costa Ribeiro; 13 - Othon Nogueira; 14 - F. Magalhães Gomes; 15 - Arthur do Prado; 16 - Alvaro Alberto; 17 - Menezes de Oliveira; 18 - Junqueira Schmidt; 19 - Yolande Monteux; 20 - Paulo R. Arruda; 21 - Giuseppe Occhialini; 22 - M. Cruz; 23 - Carlos Chagas Jr.; 24 - Ignacio Azevedo Amaral; 25 - M. D. de Souza Santos; 26 - Bernard Gross; 27 - Abrahão de Morais; 28 - Paulus Aulus Pompeia; 29 - Pe. F. X. Roser S [⁶²].

In summa, the meetings of the Symposium last 5 days: August 4, First Session; August 5, Second Session; August 6, Third and Fourth Session and August 8 Fifth Session. In each meeting, there was some presented communications followed by the discussion of others. The Proceedings were published by the Imprensa Nacional, having Arthur Moses, Bernhard Gross and Joaquim Costa Ribeiro as the Editorial Committee. The final publication only contains texts relating to the topics presented, without, however, including the respective debates and discussions. The Editorial Committee acknowledges the contribution of the Rockefeller Foundation and the Brazil-United States Institute for the help in preparing the manuscripts.

The summary of the Proceedings, divided in Part I (Report and Speeches) and Part II (Communications), is presented below.

Part I: General Report; Address by the President of the Brazilian Academy of Sciences, Prof. Arthur Moses; Address by Prof. Roquette Pinto; Address before the Brazilian Academy of Sciences by Prof. Arthur Compton.

Part II: On the fluctuations of cosmic rays (Arthur H. Compton); Cloud chambers photographs at high altitudes (Donald Hughes); The influence of a solar eclipsis on the cosmic ray intensity (Yolande Monteux, G. Occhialini and M. D. de Souza Santos); The radio-wave propagation and the cosmic rays (Adalberto Menezes de Oliveira); Cosmic ray studies in the Andes of Southern Perú (Norman Hilberry and Ann Hepburn Hilberry); On the ultra-soft component of the cosmic radiation (G. Occhialini and Mario Schönberg); On the temperature effect in cosmic radiation (F. X. Roser, S. J.); The latitude effect for the hard component of cosmic rays and evidence as to the nature of the primary radiation (William P. Jesse); On the production of mesotrons at high altitudes (Ernest O. Wollan); On the production of groups of mesotrons by high energy collisions (G. Wataghin); On a bridge method for measurement of cosmic rays with ionizing chambers (J. Costa Ribeiro); On the latitude effect of cosmic rays (B. Gross); Sur la pénétration des électrons dans la matière (Yolande Monteux); A multivibrator high tension generator (J. A. Ribeiro Saboya); Showers of penetrating particles under 30 m of Clay (Paulus A. Pompeia, M. D. de Souza Santos and G. Wataghin); A cathode following amplifier for pulse transmission in high resolving time coincidence circuits (Norman Hilberry and Paulus A. Pompeia); An electrical timing circuit to control a cloud-chamber (Paulus A. Pompeia and Ernest O. Wollan); Calculation of the plate resistance of a “Rossi” tubes system (Paulus A. Pompeia and Ernest O. Wollan); Two useful gadgets for controlled Wilson chambers (G. Occhialini and M. D. de Souza Santos); Sur une méthode de recherche de l’influence éventuelle des rayons cosmiques sur la matière vivante (René Wurmser); On the theory of the ionization chamber (B. Gross).

At 6:30 am on August 9th, 1941, Professor Arthur Compton, accompanied by his wife, returned to the United States aboard the Douglas plane operated by the Panair company²⁴ [⁹⁶, ⁹⁷, ⁹⁸, ⁹⁹, ¹⁰¹, ¹⁰², ¹⁰³, ¹⁰⁴, ¹⁰⁵, ¹¹⁴, ¹¹⁵, ¹¹⁶, ¹¹⁷, ¹¹⁸, ¹¹⁹, ¹²⁰].

On August 16, 1941, Compton wrote to Jorge Americano, who was the 4th Rector of the University of São Paulo (USP), between 1941 and 1946, not only thanking him for his hospitality and cooperation but also expressing his desire to repay them in a possible trip for Brazilian scientists to the United States [¹²¹].

I was sorry that I could not return to São Paulo after our scientific conferences were over at Rio de Janeiro. I wanted to tell you personally how much the hospitality and cooperation of your university has meant to us in carrying on our cosmic ray studies in Brazil. This opportunity for collaboration with your scientific men has greatly encouraged our own expedition. We hope that we may be able to give tangible form to our thanks by giving some comparable help to your own capable scientists as they may want to have studies done in our country.

On August 25, William P. Jesse, together with Gleb Wataghin, met with federal intervenor Fernando Costa with the aim of thanking and saying goodbye, as he would then return to the United States [¹²²].

On August 27, Compton, already in Chicago, made the following statements about the countries he visited on his mission [¹¹⁴]:

They correspond broadly to all gestures and cultural initiatives in the United States and, moreover, offer magnificent opportunities and complete reciprocity for any scientist.

Equally important was the clear evidence of a great interest and an intense desire for perfect scientific and cultural cooperation.

One of the highlights of our activities was our last week in South America, while we stayed in Rio de Janeiro. There we were, under the auspices of the Brazilian Academy of Sciences, where we met a chosen group of “physicists” and scholars, before whom we gave some lectures that were accompanied and commented by about fifty or more personalities with many of whom we were able to exchange ideas, for four days, on “solid” scientific subjects and discussing reciprocal observations on cosmic rays and related problems.

Both for us all and for our Brazilian colleagues, these conferences and discussions were the source of inspiration for more and better scientific research. It was also a great stimulus for us to find in Peru such intense expressions of cultural interest, both on the part of intellectuals and academics as well as businessmen themselves.

On October 2, 1941, a letter written by William P. Jesse [⁶⁸] was published in the São Paulo Post Office.

Your Excellency Dr. Fernando Costa, DD. Federal intervener in the state of São Paulo, – Excellency: As we leave Brazil, I wish to express to Your Excellency Personally and to the government of São Paulo, my best thanks for the great cooperation that was given to us in the performance of our scientific mission. We received all the necessary facilities to carry out our work. I ask Your Excellency Receive, for this kindness, our warmest thanks.

4.4. The recovery of the balloons

From the beginning, there was an obvious concern about the recovery of the balloons as this letter from Wataghin to Compton attests, even before he arrived in Brazil (Figure 14).

Figure 14
Copy of a letter from Wataghin to Compton that begins by talking about the recovery of some balloons brought by Pompéia, in the testing phase [¹²³].

The Brazilian Academy of Sciences had preemptively prepared a document directed at the press [¹²⁴], containing various details about the Compton mission, as well as highlighting the need for public assistance in retrieving equipment. Many newspapers based their reports on this document. However, the call for public help to recover such balloons, as well as the corresponding reward, was not widely publicized in the newspapers, often appearing only as a small paragraph within a text about the expedition, predominantly in the newspapers of the state of São Paulo [⁸¹, ⁸⁶, ¹²⁵]. Other newspapers focused more on a general explanation of the mission and the main events in the capital, Rio de Janeiro. The authors believe that the announcement was more intensely broadcasted through local radios in the areas where the balloons were expected to be found, but they were unable to obtain the necessary documentation to give more emphasis to this scenario. We only have confirmation from a telegram informing that a balloon was found by Antonio Pereira Costa in the municipality of Cachoeiras, south of Minas. He went to the police station, which in turn sent the telegram to the radio patrol (Figure 15) [¹⁰⁰, ¹²⁶, ¹²⁷].

Figure 15
Copy of a telegram informing of the recovery of a balloon [¹²⁶].

On August 21st, 1941, continuing the studies initiated by the Compton mission, at 9 am, a group of 20 balloons with cosmic ray recording devices were released in the municipality of Marilia in São Paulo. The balloons must land within the state of São Paulo and the south of Minas. People who find the balloons will be awarded prizes of 200$000²⁵ in cash and a medal, once they communicate the time and place to the nearest police station or the São Paulo radio patrol [¹⁰⁵, ¹⁰⁶, ¹⁰⁷, ¹⁰⁸].

5. Final Comments

The press material to which we had access (127 different news published in 14 newspapers), in addition to the letters between Compton and Wataghin, for example, shows that a significant space was given to Compton scientific mission, in 1941, by Brazilian written midia, equivalent to what happened in 1934, with Fermi’s trip to Brazil. Only Einstein’s visit in 1925 deserved more attention [¹²⁸].

It is true that the United States support to the expedition of a North scientific leader as Arthur Compton to Latin America was part of their policy of cultural proximity and their efforts to neutralize the influence of the Axis powers in this part of the Americas [²⁷]. There was a similar scope in Fermi’s visit, with which the Italian fascist government sought to gain sympathy in South America, in a period when Brazilian science was still very incipient. But it is also true that it contributes to the consolidation of Cosmic Ray Physics in Brazil.

Indeed, the Compton mission, in addition to bringing public visibility to the study of cosmic rays and fostering interest among students of the time, was an important milestone for the subsequent implementation of funding by the Rockefeller Foundation, as indicated in Ref. [²⁷].

There is a second aspect to be addressed in order to understand the active attitude of the USP physicists in their support for Compton’s expedition. This concerns the most significant scientific collaboration, under Compton’s leadership, in the field of cosmic rays. Through this collaboration, the USP physicists expected and obtained support for the supply of equipment for their research, as may be inferred from W.P. Jesse’s letter to Wataghin, confirming, “I am enclosing a copy of a letter from the Indiana Steel Company, which they sent me in reply to my inquiries about the magnet that you are interested in. We are also sending a copy of this to the Rockefeller Foundation, which sent us, sometime ago, a list of the things that you need […] We are sending to Professor Occhialini some mercury-vapor lamps, and we have on order for him some tungsten lamps.” The success of this second aspect was, however, greater than the expectations of the USP physicists, since the reference to the Rockefeller Foundation in the letter cited above deserves expansion. In fact, it could be said that Compton became the principal guarantor for the continued funding that the Rockefeller Foundation secured for the USP Physics Department from this date onwards, and for many years, even after the end of the Second World War. On 23rd January 1942, the Director of the Rockefeller Foundation, H. M. Miller, who had accompanied Compton on his visit to Brazil, wrote requesting his opinion about an application for support made by Wataghin for an expedition to Peru, which had been discouraged by Miller. However, Miller confirms, “although at the time I discouraged a formal request for this purpose, we might be able to reopen the question if assured of the importance of the work to be done … before taking any step in this direction, we wish to have your considered opinion.” As Pompéia remembered much later: “When the war finished we had a very good relationship with Dr Harry Müller Jr [sic] of the Rockefeller Foundation. I knew him in ’41 when I came with the American expedition.”

In any case, from the point of view of Brazilian physics, Alfredo Marques, who collaborated with Lattes, has a very good impression of that time [⁴¹]:

The great merit of [Compton] expedition was its final: ended with a symposium bringing together Brazilian physicists and of Compton team members who presented and discussed results of their recent work. It was probably the first international physics meeting held in the country, in August 1941. It was attended by Compton and his Proceedings were published in supplement to that year’s volume of the Annals of the Brazilian Academy of Sciences. O text deserves to be read as it is very revealing of the high level at which they developed scientific work in the country, including the explicit recognition of a large scientific authority such as Arthur Compton. Compton’s speech was not a conventional filigree of someone who thanks them for the hospitality and leaves taking everything what interested him, the data from measurements of the effect of latitude; its authority and scientific responsibility were too great to harbor this type of behavior. At several points in his speech he recognizes the relevance and value of the works developed in the Department of Physics at USP, giving it the greatest respect. Unfortunately, the entry into World War II, first by the USA, in December 1941, and Brazil, right at the beginning of the following year, profoundly changed the destinies of all.

In addition, we can’t forget that Cesar Lattes was a brilliant student in Wataghin’s Cosmic Rays group since 1943, and, in 1947-8, was the only participant of both natural and artificial detection of the pion [¹²⁹]. Based on the enormous success of these scientific achievements, José Leite Lopes and several Brazilian scientists, politicians and nationalist military personnel [⁷²] made a great effort to create the Centro Brasileiro de Pesquisas Físicas, in Rio de Janeiro, hopping to establish appropriate conditions for the development of Nuclear Physics and Particle Physics in Brazil. From the point of view of Brazilian scientific polices, from the beginning of its institutionalization in the country the Cosmic Rays area may be considered a crucial milestone.

Acknowledgments

We are pleased to thank Marcio José Menon and Cássio Leite Vieira for useful suggestions and discussions, and Arthur Thompson Motta for kindly sharing with us some documents from his grandfather Arthur Moses as well as for his interest in our research. We are also grateful to two anonymous reviewers for their criticisms and suggestions that contributed to making the article clearer and more accessible to a wider audience.

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  Missão Compton, Jornal do Commercio, Rio de Janeiro, 3 de agosto de 1941.
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  A missão Compton no Rio de Janeiro, Correio Paulistano, São Paulo, 5 de agosto de 1941.
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  Preleção do prof. Artur Compton na Academia Brasileira de Ciências, Diário Carioca, Rio de Janeiro, 5 de agosto de 1941.
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  Seminário sobre raios cósmicos, Jornal do Brasil, Rio de Janeiro, 5 de agosto de 1941.
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  Missão Compton, Jornal do Commercio, Rio de Janeiro, 5 de agosto de 1941.
• ^[98]
  Missão Compton, Jornal do Commercio, Rio de Janeiro, 6 de agosto de 1941.
• ^[99]
  Raios cósmicos, o problema do dia, O Globo, Rio de Janeiro, 5 de agosto de 1941.
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  Seminário de raios cósmicos, Jornal do Commercio, Rio de Janeiro, 16 de agosto de 1941.
• ^[101]
  Almoço oferecido pelo ministro do exterior, Diário de Notícias, Rio de Janeiro, 5 de agosto de 1941.
• ^[102]
  Homenagem aos membros da missão cientifica ``yankee'', Correio Paulistano, São Paulo, 3 de agosto de 1941.
• ^[103]
  Um almoço ao professor Arthur Compton, Diário Carioca, Rio de Janeiro, 3 de agosto de 1941.
• ^[104]
  Um almoço a estrangeiros ilustres, Jornal do Commercio, Rio de Janeiro, 5 de agosto de 1941.
• ^[105]
  A missão Compton na Academia Brasileira de Ciências, O Estado de São Paulo, São Paulo, 5 de agosto de 1941.
• ^[106]
  A mesa de maior destaque no restaurante social, O Globo, Rio de Janeiro, 4 de agosto de 1941.
• ^[107]
  Recepção à missão Compton, O Imparcial, Rio de Janeiro, 6 de agosto de 1941.
• ^[108]
  Adiada a partida do professor Compton, O Globo, Rio de Janeiro, 5 de agosto de 1941.
• ^[109]
  Se a tocha da civilização deve continuar brilhando, cabe à América conserva-la, Correio Paulistano, São Paulo, 8 de agosto de 1941.
• ^[110]
  O sr. Arthur H. Compton na Hora do Brasil, Diário de Notícias, Rio de Janeiro, 7 de agosto de 1941.
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  Missão Compton, Jornal do Commercio, Rio de Janeiro, 7 de agosto de 1941.
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  Brasil e Estados Unidos devem manter acesa a tocha da civilização, O Globo, Rio de Janeiro, 7 de agosto de 1941.
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  Raios cósmicos, O Imparcial, Rio de Janeiro, 8 de agosto de 1941.
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  A última reunião de Seminário da Missão Científica norte-americana, Diário de Notícias, Rio de Janeiro, 9 de agosto de 1941.
• ^[115]
  Um congresso de física e matemática no Rio, O Globo, Rio de Janeiro, 9 de agosto de 1941.
• ^[116]
  Regressa aos Estados Unidos o prof. Artur (sic.) H. Compton, Correio Paulistano, São Paulo, 9 de agosto de 1941.
• ^[117]
  Regressou aos Estados Unidos a Missão Compton, Correio Paulistano, São Paulo, Agosto de 1941.
• ^[118]
  Regressa aos EE. UU. O chefe da Missão cientifica que veio estudar os raios cósmicos no Brasil, Diário Carioca, Rio de Janeiro, 9 de agosto de 1941.
• ^[119]
  última reunião da missão Compton, Folha da Manhã, São Paulo, 9 de agosto de 1941.
• ^[120]
  Regresso da missão Compton, O Estado de São Paulo, São Paulo, 9 de agosto de 1941.
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  A.H. Compton to J. Americano (Instituto de Física da Universidade de São Paulo, São Paulo, 1941), correspondence, available in: http://acervo.if.usp.br/uploads/IF/DF/VI-0/IF-DF-VI-02-21-0000-02114-0.pdf, accessed in: 20/06/2024.
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  Experiencias sobre os raios cósmicos, Correio Paulistano, São Paulo, 23 de agosto de 1941.
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  Pesquisas sobre os raios cósmicos, Correio Paulistano, São Paulo, 20 de agosto de 1941.
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  Missão Compton, Jornal do Commercio, Rio de Janeiro, 9 de agosto de 1941.
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• 1
  Sometimes referred to as Compton Expedition.
• 2
  The University of São Paulo (USP) was established by merging the newly created Faculty of Philosophy, Sciences, and Literature (FFCL) with existing institutions such as the Polytechnic School of São Paulo, the Higher School of Agriculture “Luiz de Queiroz”, the School of Medicine, the Law School, and the School of Pharmacy and Dentistry.
• 3
  That same year, he became Wataghin’s assistant in the Rational Mechanics chair, dedicating himself to the construction of measurement devices and electrical circuits necessary for the research in which he was involved with Wataghin. By the end of 1938, as a British Council Fellow, he went to the Cavendish Laboratory at the University of Cambridge, England, his stay was interrupted by the start of the WWII. There, with his exceptional skills as an experimental physicist, he developed a high-resolution electronics technique that ended up allowing the group, with Wataghin and Pompéia, to discover the penetrating showers in cosmic rays.
• 4
  Pompéia was an Electrical Engineer from the Polytechnic School of USP (1935), and graduated in Physics in 1939. In 1940, invited by Compton, he went on a study and improvement trip to the University of Chicago, commissioned by the Government of São Paulo. At this University, he worked under the direction of Norman Hilberry, developing new techniques for measuring cosmic radiation and improving electrical circuits. In July 1941, he interrupted his research to participate in the Compton Expedition. He was one of the main organizers of the Aeronautical Technological Institute, in São José dos Campos, one of the most important engineering schools in the country.
• 5
  In his youth, Oscar Sala, coincidentally, was in Bauru, the city where he received his basic education, when some sounding balloons were launched from the Compton Mission, in 1941 (Figure 1). At that time he was in the second year at the Polytechnic School and went to watch the launch of some balloons. It was on this occasion that he met Wataghin, who convinced him to transfer to Physics. Wataghin, being a foreigner, could not participate in the national war effort to which the Physics Department was supposed to be involved with. Thus, he decided to continue his studies in cosmic rays and invited Sala to help him. His first task was to think about and develop a much more sophisticated equipment than that which had previously been used by Damy and Pompéia. One can immagine how scarse electronic components were during war time. The construction of sophisticated equipment, at that time, required a lot of dedicated work from Sala, including the problem of winding the transformers and building special capacitors that do not existed at the time. In spite of all difficulties, after a year of tough work, the equipment was ready and in operation due to Sala effort. This achievement allowed the continuity of the studies of the penetrating showers.
• 6
  Born in France, she was the first woman to graduate in physics in Brazil. She was also the only Brazilian female scientist at the Cosmic Ray Symposium at Rio de Janeiro. She is the participant no. 19 of the official photo of the event, as can be seen in Section ⁴. Although there are two communications in the Proceedings signed by Ann Hepburn Hilberry and her husband, Norman Hilberry, but it is not clear if she actually attended the Symposium.
• 7
  Providence wanted Lattes’ father to know Wataghin. He advised his son to go and talk to the eminent professor about the possibility of studying Physics. The father’s guidance was followed. Wataghin told the young Cesare that it was possible for him not to take the pre-university exam. Thus, Lattes completed one year less of high school and ended up graduating in Physics, in 1943, at age 19.
• 8
  The measurements were taken in São Paulo at 800 m above sea level.
• 9
  Oscar Sala once said that, in a conversation with Governor Adhemar de Barros, Wataghin went to ask for financial help. Impressed, the governor said to him, opening a drawer: – Prof. Wataghin, how much do you need? However, it is not clear whether the occasion is the same reported here or not. Another curiosity, is the fact that the decree creating USP, in 1934, was signed by another federal intervener in the State of São Paulo, who was Armando de Sales Oliveira.
• 10
  Ironically, there were delays in the release of North American financing, which meant that the CSN was only inaugurated in 1946, without the presence of Getulio, in political ostracism.
• 11
  For his method of making the paths of electrically charged particles visible by vapour condensation.
• 12
  The complete collection of the publication Ciência para todos has been digitized by the National Library of Brazil.
• 13
  Acronym for Departamento de Imprensa e Propaganda, in Portuguese. Created in 1939 by the President Getulio Dornelles Vargas, it served as a propaganda and government censorship instrument during the Estado Novo. In 1945 it was replaced by the National Information Bureau.
• 14
  See comments about the main strategic interests of the Vargas Government in Section ¹.
• 15
  Some report at the time mistakenly identified him as a North American scientist and in other reports his name appears as Pandos Pompéia.
• 16
  All translations of journalistic news were made by the authors.
• 17
  Discovered by the American scientist Carl D. Anderson in 1936, the name mesotron was coined by him and Seth Neddermeyer in a letter to Nature, in 1938, composed by the prefix “meso”, which in Greek means mid, as its mass is between the mass of the electron and that of the proton. It was later renamed muon.
• 18
  Building where the headquarters of the Secretary of Agriculture and Supply of the State of São Paulo are located today.
• 19
  Also known as Expresso Cruzeiro do Sul, it connected the cities of Rio de Janeiro and São Paulo, during the years 1929 to 1950, by the Central Railroad of Brazil.
• 20
  Luxury hotel located in the neighborhood of Glória, in Rio de Janeiro. Room 400 hosted Albert Einstein, for a week in May 1925, during his visit to the city. The Hotel remained open for 86 years until it closed in 2008. The building is currently undergoing renovations to become a residential building.
• 21
  Today is the Institute of Philosophy and Social Sciences of the Federal University of Rio de Janeiro.
• 22
  Named after its proposer, the Swedish physicist and Nobel Laurent Hannes Olof Gösta Alfvén.
• 23
  Current Federal University of Rio de Janeiro.
• 24
  Leading Brazilian airline between the 1930s and 1950s.
• 25
  The currency of the time was the Real (popularly known as réis), a currency which still portrayed the times of colonial Brazil, was replaced by the Cruzeiro in 1942. It is estimated that 1 real was worth the equivalent of the current exchange rate in 2023 of 0.0061 US dollars.

Publication Dates

• Publication in this collection
  27 Sept 2024
• Date of issue
  2024

History

• Received
  11 May 2024
• Reviewed
  30 June 2024
• Accepted
  30 July 2024