##### Document Text Contents

Page 1

EARLY HISTORY OF COSMIC RA Y STUDIES

Page 2

ASTROPHYSICS AND

SPACE SCIENCE LIBRARY

A SERIES OF BOOKS ON THE RECENT DEVELOPMENTS

OF SPACE SCIENCE AND OF GENERAL GEOPHYSICS AND ASTROPHYSICS

PUBLISHED IN CONNECTION WITH THE JOURNAL

SPACE SCIENCE REVIEWS

Editorial Board

R. L. F. BOYD, University College, London, England

L. GOLDBERG, Kitt Peak National Observatory, Tucson, Ariz., U.S.A.

C. DE JAGER, University of Utrecht, The Netherlands

J. KLECZEK, Czechoslovak Academy of Sciences, Ondrejov, Czechoslovakia

Z. KOPAL, University of Manchester, England

L. I. SEDOV, Academy of Sciences of the U.S.S.R., Moscow, U.S.S.R.

Z. SVESTKA, Laboratory for Space Research, Utrecht, The Netherlands

VOLUME 118

PROCEEDINGS

Page 215

216 P. Auger

photographs, due probably to slow protons, and suggesting the presence of neutrons in

the beam. But the striking feature was the density of electron tracks, sometimes so

thick that the cloud chamber looked like filled with a heavy rainfall (see Fig. 3): in

this case we thought that the chamber had been striken by the axial part of the

shower, probably the direction of the incoming primary particle. Some photographs

showed much less dense tracks, characteristic of the periphery of the showers. We did

also some work with two chambers, situated vertically above one another and

separated by screen of lead, and could make visible the multiplication effect of the

screen.

But the main surprise came when I tried to evaluate the energy of the incoming

primary particles. For that purpose I had to evaluate the total number of electrons,

and also the mean value of their energy. The total number could be deduced from the

density of tracks per square meter and the distance at which the coincidences could be

obtained. For that last variation of number of showers with distance, it was clear that

showers of much more extension did exist. Anyway, with a total surface of between 104

and 105 square meters this meant a munimum of 106 particles in the showers of large

extension. Now as to the energy of the electron, not having at my disposal at that

time a cloud chamber in a magnetic field, I had to admit that they had at least the

critical energy in air, that is 108 eV. By another method, the consideration of the total

screen of air between the origin of the showers and the instruments, the same value

can be derived from the Bhabha-Heitler calculations.

Taking that mean value of 1011 eV and the total number of 106 electrons and taking

into account the loss of energy by crossing the atmosphere, I came to the conclusion,

rather astonishing at that time, that particles of at least 1015 eV arrived at the top of

the atmosphere (Auger et al., 1938, 1939a, b, 1948, 1949). The number per square

meter of these primary particles could also be evaluated, and taking only the particles

Fig. 2. Au sol (Labo.).

Page 216

Proof of the Very High Energies Carried by Some of the Primary Particles 217

Fig. 3

with an energy higher than 1015 eV their number was found of the ordered one per

day on 10 square meters. Of course the number of particles with smaller energy, say

1012 eV, was more than 10 times larger.

As for the energy spectrum of the primaries responsible for the extensive showers we

tried to deduce it from the number of showers obtained at different altitudes. Having

done some experiments with three to nine coincidence counters installed in an airplane

with a total horizontal extension of 15 meters, we found at the altitude of 7250

meters a fifty fold increase. We found also a strong increase of the density of the tracks

in the big showers. At first sight, the spectrum seemed to be of an exponential form,

the number of showers with an energy higher than E being roughly proportional to

£-2.

Anyway the existence of a large number of particles striking our atmosphere with

an energy of that magnitude could not be easily explained. Since the time of our

discovery, in 1938, the existence of these high energy particles has been confirmed and

even much higher energies have been measured by different authors, 1018 and perhaps

even 10 20 in very exceptional cases. How particles with such energies are produced is

not fully understood even if some interesting theories have been proposed, for instance

by Fermi, involving large and extended magnetic fields in space. It is presently admitted

that the primary particles responsible for the EAS are nuclei, mostly protons, and

some heavier ones. The initiation of the shower takes place at very high altitude, say

20 km above ground, and consists in a first collision between the high energy primary

particle and the nucleus of an atom of the air. All sorts of particles are then produced,

but the main part of the shower after a few km of atmosphere, are electrons and

positrons, with a certain proportion of muons, - those which are counted under

10-20 cm of lead -, of pions, of light nuclei and hadrons. So the total analysis of the

phenomenon tends to be rather complicated, and has been studied by a large number

of physicists. Many publications have been made since our first observation of long

distance coincidences leading to the discovery of the extensive showers.

Page 430

Name Index 443

Stozhkov, 367

Street, J. c., 125, 140, 141, 155-157,288,387

Suga, K., 222-224, 244, 245

Sugerman, N., 401

Swann, W. F. G., 265, 267, 387,428

Swetnick, 260

Syrovatskii, S. 1.,418-420,423

Szilard, L., 385

Takagi, S., 347

Taketani, M., 192, 210, 221, 285, 287, 290,

292, 293, 340

Takeuchi, M., 137, 138, 140, 142, 189, 197,

220,288

Takibayev, 234

Tamaki, H., 197,290,292,293

Tamm, 1.,134,227,286,339,340,342

Tamura, Y., 188

Tanaka, 224

Tanikawa, Y., 290-292

Tarrant, G. T. P., 100

Tate, J. T., 263

Telegdi, V., 401

Teller, E., 267, 387, 388, 428

Terada, T., 187

Thales, 9, 10, 14

Thambyahpillai, T., 383

Thiesoen,381

Thompson, R. W., 129, 311, 313, 317-319

Thomson, J. J., 10, 12

Tidman, D. A., 324, 328

Tinlot, J., 251

Tomonoga, S., 188, 189, 192, 197-199, 285,

286, 289-293

Tongiorgi, V. C., 394

Torney, 243

Townsend, 65

Trabacchi, 65

Treiman, S. B., 394

Tremblay, J., 251

Tripp, R. D., 330

Trost, 193

Turkot,349

Turner, R., 195

Tuve, M., 255

Tuvim, 47, 225

Tverskoy, B. A., 368

Tyapkin, A. A., 334

Uhlenbeck, G., 289, 340, 343

Umeda, K., 286

Unsold, 414, 416

Urey, H. c., 388,401

Viiisiilii, 107

Valera, de, 308

Vallarta, M. S., 68, 200, 205, 265, 270, 380,

387,389,394,398,428

Vallauri,65

Valley, G., 265

Van Allen, J., 225, 270,406,421

Van Heerden, I. J., 383

Varfolomeev, A. A., 330, 334

Vashakidze, 416

Vavilov, 226, 234, 372

Vavilov, S. I., 359

Veksler, V., 227,228, 345, 363

Verigo, A. B., 225

Vernov, N., 357, 359, 360, 362-367, 371, 372

Vernov, 225, 227

Vick, F. A., 304

Victor, 79

Vieweg,29

Vityaz,365

Vladimirskii, 414, 415

Vogt,270

Volkov, E. I., 350, 351

Von Halban, 257

Wada, M., 196, 200, 203

Waddington, J., 272-274

Wallace, 423

Walraven, 418

Wambacher, H., 28, 29, 210

Wataghin, G., 344

Wataghin,65

Watagin, 235, 299

Watanabe, S., 223, 291

Watase, Y., 197-199, 219-224, 289

Webster, 422

Wegener, 384

Weicziicher, 222

Weischedel, 83

Weisskopf, V. F., 343

Weizsiicker, C. F., 51,152,341

Wentzel, G., 291, 394, 399

Weyssennoff, J., 295

Wheeler, J. A., 112, 265, 295, 297, 387

Wick, G., 340, 342

Wienberg, L., 263

Wigand, 76

Wigner, E., 385

Wilkinson, D. H., 332

Williams, E. J., 126, 152, 156-158,341

Williams, R., 222, 239, 299

Wilson, A. H., 342

Wilson, C. T. R., 11-14, 17,47,48,50,99, 101,

109, 118, 126, 149, 161, 24~ 349

Wilson, J. G., 145, 149-151, 154-158,299,304,

375,384

Page 431

444

Wilson, V., 385, 387

Winckler, J., 266, 268, 271, 273, 274

Winzen, 0., 263

Wolf, E., 20, 21, 75

Wolfendale, 419

Wollan,E.0.,291,300, 302,387,389

Wood,13

Wordie, J. M., 103, 104, 109, 110

Wright, C., 401

Wulf, Th., 8,14,18,19,75-77

Wynn-Williams, C. E., 100

Yagi, T., 203

Yamaguchi, Y., 220, 221289

Yamasaki, F., 138, 187, 189, 190

York, C. M., 313, 318,401

Name Index

York, H., 273, 287

Yoshida, S., 202

Yuan, L. C. L., 391

Yukawa, H., 10, 126, 127, 133, 134, 157-159,

161, 163, 164, 187, 188, 195, 210, 220,

285, 286, 288, 289, 291, 292, 302, 340-

342,344

Zachariasen, W., 385,401

Zatsepin, G. T., 51, 225, 229, 230, 345, 347,

367

Zeleny, 107

Zhdanov, A. P., 228,231,233,234

Zhirov, O. V., 348

Zwicky, F., 412, 419

EARLY HISTORY OF COSMIC RA Y STUDIES

Page 2

ASTROPHYSICS AND

SPACE SCIENCE LIBRARY

A SERIES OF BOOKS ON THE RECENT DEVELOPMENTS

OF SPACE SCIENCE AND OF GENERAL GEOPHYSICS AND ASTROPHYSICS

PUBLISHED IN CONNECTION WITH THE JOURNAL

SPACE SCIENCE REVIEWS

Editorial Board

R. L. F. BOYD, University College, London, England

L. GOLDBERG, Kitt Peak National Observatory, Tucson, Ariz., U.S.A.

C. DE JAGER, University of Utrecht, The Netherlands

J. KLECZEK, Czechoslovak Academy of Sciences, Ondrejov, Czechoslovakia

Z. KOPAL, University of Manchester, England

L. I. SEDOV, Academy of Sciences of the U.S.S.R., Moscow, U.S.S.R.

Z. SVESTKA, Laboratory for Space Research, Utrecht, The Netherlands

VOLUME 118

PROCEEDINGS

Page 215

216 P. Auger

photographs, due probably to slow protons, and suggesting the presence of neutrons in

the beam. But the striking feature was the density of electron tracks, sometimes so

thick that the cloud chamber looked like filled with a heavy rainfall (see Fig. 3): in

this case we thought that the chamber had been striken by the axial part of the

shower, probably the direction of the incoming primary particle. Some photographs

showed much less dense tracks, characteristic of the periphery of the showers. We did

also some work with two chambers, situated vertically above one another and

separated by screen of lead, and could make visible the multiplication effect of the

screen.

But the main surprise came when I tried to evaluate the energy of the incoming

primary particles. For that purpose I had to evaluate the total number of electrons,

and also the mean value of their energy. The total number could be deduced from the

density of tracks per square meter and the distance at which the coincidences could be

obtained. For that last variation of number of showers with distance, it was clear that

showers of much more extension did exist. Anyway, with a total surface of between 104

and 105 square meters this meant a munimum of 106 particles in the showers of large

extension. Now as to the energy of the electron, not having at my disposal at that

time a cloud chamber in a magnetic field, I had to admit that they had at least the

critical energy in air, that is 108 eV. By another method, the consideration of the total

screen of air between the origin of the showers and the instruments, the same value

can be derived from the Bhabha-Heitler calculations.

Taking that mean value of 1011 eV and the total number of 106 electrons and taking

into account the loss of energy by crossing the atmosphere, I came to the conclusion,

rather astonishing at that time, that particles of at least 1015 eV arrived at the top of

the atmosphere (Auger et al., 1938, 1939a, b, 1948, 1949). The number per square

meter of these primary particles could also be evaluated, and taking only the particles

Fig. 2. Au sol (Labo.).

Page 216

Proof of the Very High Energies Carried by Some of the Primary Particles 217

Fig. 3

with an energy higher than 1015 eV their number was found of the ordered one per

day on 10 square meters. Of course the number of particles with smaller energy, say

1012 eV, was more than 10 times larger.

As for the energy spectrum of the primaries responsible for the extensive showers we

tried to deduce it from the number of showers obtained at different altitudes. Having

done some experiments with three to nine coincidence counters installed in an airplane

with a total horizontal extension of 15 meters, we found at the altitude of 7250

meters a fifty fold increase. We found also a strong increase of the density of the tracks

in the big showers. At first sight, the spectrum seemed to be of an exponential form,

the number of showers with an energy higher than E being roughly proportional to

£-2.

Anyway the existence of a large number of particles striking our atmosphere with

an energy of that magnitude could not be easily explained. Since the time of our

discovery, in 1938, the existence of these high energy particles has been confirmed and

even much higher energies have been measured by different authors, 1018 and perhaps

even 10 20 in very exceptional cases. How particles with such energies are produced is

not fully understood even if some interesting theories have been proposed, for instance

by Fermi, involving large and extended magnetic fields in space. It is presently admitted

that the primary particles responsible for the EAS are nuclei, mostly protons, and

some heavier ones. The initiation of the shower takes place at very high altitude, say

20 km above ground, and consists in a first collision between the high energy primary

particle and the nucleus of an atom of the air. All sorts of particles are then produced,

but the main part of the shower after a few km of atmosphere, are electrons and

positrons, with a certain proportion of muons, - those which are counted under

10-20 cm of lead -, of pions, of light nuclei and hadrons. So the total analysis of the

phenomenon tends to be rather complicated, and has been studied by a large number

of physicists. Many publications have been made since our first observation of long

distance coincidences leading to the discovery of the extensive showers.

Page 430

Name Index 443

Stozhkov, 367

Street, J. c., 125, 140, 141, 155-157,288,387

Suga, K., 222-224, 244, 245

Sugerman, N., 401

Swann, W. F. G., 265, 267, 387,428

Swetnick, 260

Syrovatskii, S. 1.,418-420,423

Szilard, L., 385

Takagi, S., 347

Taketani, M., 192, 210, 221, 285, 287, 290,

292, 293, 340

Takeuchi, M., 137, 138, 140, 142, 189, 197,

220,288

Takibayev, 234

Tamaki, H., 197,290,292,293

Tamm, 1.,134,227,286,339,340,342

Tamura, Y., 188

Tanaka, 224

Tanikawa, Y., 290-292

Tarrant, G. T. P., 100

Tate, J. T., 263

Telegdi, V., 401

Teller, E., 267, 387, 388, 428

Terada, T., 187

Thales, 9, 10, 14

Thambyahpillai, T., 383

Thiesoen,381

Thompson, R. W., 129, 311, 313, 317-319

Thomson, J. J., 10, 12

Tidman, D. A., 324, 328

Tinlot, J., 251

Tomonoga, S., 188, 189, 192, 197-199, 285,

286, 289-293

Tongiorgi, V. C., 394

Torney, 243

Townsend, 65

Trabacchi, 65

Treiman, S. B., 394

Tremblay, J., 251

Tripp, R. D., 330

Trost, 193

Turkot,349

Turner, R., 195

Tuve, M., 255

Tuvim, 47, 225

Tverskoy, B. A., 368

Tyapkin, A. A., 334

Uhlenbeck, G., 289, 340, 343

Umeda, K., 286

Unsold, 414, 416

Urey, H. c., 388,401

Viiisiilii, 107

Valera, de, 308

Vallarta, M. S., 68, 200, 205, 265, 270, 380,

387,389,394,398,428

Vallauri,65

Valley, G., 265

Van Allen, J., 225, 270,406,421

Van Heerden, I. J., 383

Varfolomeev, A. A., 330, 334

Vashakidze, 416

Vavilov, 226, 234, 372

Vavilov, S. I., 359

Veksler, V., 227,228, 345, 363

Verigo, A. B., 225

Vernov, N., 357, 359, 360, 362-367, 371, 372

Vernov, 225, 227

Vick, F. A., 304

Victor, 79

Vieweg,29

Vityaz,365

Vladimirskii, 414, 415

Vogt,270

Volkov, E. I., 350, 351

Von Halban, 257

Wada, M., 196, 200, 203

Waddington, J., 272-274

Wallace, 423

Walraven, 418

Wambacher, H., 28, 29, 210

Wataghin, G., 344

Wataghin,65

Watagin, 235, 299

Watanabe, S., 223, 291

Watase, Y., 197-199, 219-224, 289

Webster, 422

Wegener, 384

Weicziicher, 222

Weischedel, 83

Weisskopf, V. F., 343

Weizsiicker, C. F., 51,152,341

Wentzel, G., 291, 394, 399

Weyssennoff, J., 295

Wheeler, J. A., 112, 265, 295, 297, 387

Wick, G., 340, 342

Wienberg, L., 263

Wigand, 76

Wigner, E., 385

Wilkinson, D. H., 332

Williams, E. J., 126, 152, 156-158,341

Williams, R., 222, 239, 299

Wilson, A. H., 342

Wilson, C. T. R., 11-14, 17,47,48,50,99, 101,

109, 118, 126, 149, 161, 24~ 349

Wilson, J. G., 145, 149-151, 154-158,299,304,

375,384

Page 431

444

Wilson, V., 385, 387

Winckler, J., 266, 268, 271, 273, 274

Winzen, 0., 263

Wolf, E., 20, 21, 75

Wolfendale, 419

Wollan,E.0.,291,300, 302,387,389

Wood,13

Wordie, J. M., 103, 104, 109, 110

Wright, C., 401

Wulf, Th., 8,14,18,19,75-77

Wynn-Williams, C. E., 100

Yagi, T., 203

Yamaguchi, Y., 220, 221289

Yamasaki, F., 138, 187, 189, 190

York, C. M., 313, 318,401

Name Index

York, H., 273, 287

Yoshida, S., 202

Yuan, L. C. L., 391

Yukawa, H., 10, 126, 127, 133, 134, 157-159,

161, 163, 164, 187, 188, 195, 210, 220,

285, 286, 288, 289, 291, 292, 302, 340-

342,344

Zachariasen, W., 385,401

Zatsepin, G. T., 51, 225, 229, 230, 345, 347,

367

Zeleny, 107

Zhdanov, A. P., 228,231,233,234

Zhirov, O. V., 348

Zwicky, F., 412, 419