Hareyama, M

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29th International Cosmic Ray Conference Pune (2005) 3, 1720Proton and Helium spectra obtained by RUNJOB experimentM. Hareyama , V.A.Derbina, V.I. Galkin, Y. Hirakawa, Y. Horiuchi, M. Ichimura,N. Inoue,E. Kamioka, T. Kobayashi, V.V. Kopenkin, S. Kuramata,A.K. Managadze, H. Matsutani, N.P. Misnikova, R.A. Mukhamedshin, S. Nagasawa,R. Nakano, M. Namiki, M. Nakazawa, H. Nanjo, S.N. Nazarov, S. Ohata,H. Ohtomo,V.I.Osedlo, D.S. Oshuev, P.A. Publichenko, I.V. Rakobolskaya,T.M. Roganova, C. Saito, G.P. Sazhina, H. Semba 	, T. Shibata, D. Shuto,H. Sugimoto  , R. Suzuki, L.G. Sveshnikova, V.M. Taran, N. Yajima, T. Yamagami,I.V. Yashin, E.A. Zamchalova, G.T. Zatsepinand I.S. Zayarnaya(RUNJOB collaboration, RUssia-Nippon JOint Balloon collaboration)(1) Major in Pure and Applied Physics, Science and Engineering, Waseda University, Tokyo 169-8555, Japan(2) Physical Department of Moscow State University, Moscow 119899, Russia(3) D.V. Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119899, Russia(4) Faculty of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan(5) Department of Physics and Mathematics, Aoyama Gakuin University, Tokyo 157-8572, Japan(6) Multimedia Information Research Division, National Institute of Informatics, The Ministry of Education,Tokyo 101-8430, Japan(7) School of Medicine, Hirosaki University, Hirosaki 036-8562, Japan(8) P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow 117924, Russia(9) Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara 229-8510, Japan(10) Faculty of Comprehensive Welfare, Urawa University, Urawa 336-0974, Japan(11) Shonan Institute of Technology, Fujisawa 251-8511, JapanPresenter: M. Hareyama (m-hare@waseda.jp), jap-hareyama-M-abs1-og11-oralThis report presents the final results of the proton and the helium spectra in the energy range between 10 and500 TeV/nucleon obtained by RUNJOB experiments as trans-Siverian long duration balloon. A proton withPeV energy was directly detected in 1995 campaign. This is the first detection of proton event more than10eV in direct observation. Our proton spectrum is in good agreement with other results such as JACEE andSOKOL, but the intensity of the helium component is nearly half that obtained by them, while it agrees withMUBEE. The slopes of the spectra of these two elements in RUNJOB are almost parallel with power index of2.7–2.8 in the energy range 10–500 TeV/nucleon. These results suggests simply acceleration and propagationmechanism of cosmic rays depending on particle rigidity.1. IntroductionProton and helium elements are the most predominant cosmic-ray (CR) components over the wide energyranges, providing us the reliable energy spectra with rich statistics as compared with other heavier elements.These two components give us a vital clue for the understanding of the acceleration mechanism of CRs andtheir propagation processes in the Galaxy. The energy dependence of the flux ratio, helium/proton, brings usimportant information, for instance the contribution of the reacceleration during the propagation might appearin the low energy region around 1 GeV/nucleon [1], and the non-linear effect in the shock acceleration inthe source might be observed in the higher energy region100 GeV/nucleon [2]. It is also quite interestingand critical if the acceleration limit appears in the proton spectrum somewhere around 1 PeV, and the heliumcomponent becomes abundant after the drop of the proton spectrum. However, there were some observationsin the energy region more than 100 GeV/nucleon, particularly a few ones in several hundreds TeV region with18 M. Hareyama et al.small statistics, in which are removed troublesome effects such as the ionization loss, solar modulation, thecomplicated energy-dependent collision cross section and so forth.With these backgrounds, we commenced a joint balloon experiment with use of the emulsion chambers in1995. Eleven balloon flights have been launched from the Kamchatka peninsula since then and ten of themwere successfully recovered near the Volga region after a level flight of  150 hrs. One balloon as RUNJOB-VII failed due to the malfunction of the auto-safety system. The total exposure of these campaigns amounts to575 m  hrs, with an average flight altitude of  km corresponding to  10 g/cm  of atmospheric depth.This paper is focused only to the final results of proton and helium spectra based on full exposure of RUNJOBflights except for RUNJOB-VII, while we omit the technical details because of reporting them in Apanasenko etal.(2001)[3] as the flight performance, such as the trajectories and the altitude variations of RUNJOB balloons(see also Furukawa et al., 2003 [4]), and detailed descriptions of analysis procedures such as the chamberefficiency, energy determination (see also Hareyama et al., 2003 [5]) , charge determination, and so on. Theheavy components and all particle spectra by our experiment were presented in the other report by Ichimura etal. for heavy components [6] and Sveshnikova et al. for all particle spectrum and avarage mass [7] in the samesession of this proceedings and see also Derbina et al. [8].2. Results and DiscussionIn Figure 1, we demonstrate the proton and the helium spectra obtained by our ten flights together with theresults of other measurements such as JACEE [9], SOKOL [10] and MUBEE [11] in the same energy range asRUNJOB, where the vertical axis is multiplied by   in order to emphasize spectral features. Also shownare the results at lower energies obtained by AMS [12, 13], BESS [14] and IMAX [15]. The later groupsprovide remarkable spectra with excellent energy resolution and high statistics, although the energy region of0.5–100 GeV/nucleon does not cover the energy region of our interest here. Their spectra appear to continuesmoothly to energies of1 TeV/nucelon, although we can not conclude whether the extrapolation of theirhelium spectra is more likely to connect to the RUNJOB or JACEE plots.We note that a PeV-proton was detected in the first 1995 flight, but no new proton with PeV energy hasbeen observed in other flights. This proton detected directly is the first directly evidence to be accelerated toPeV/nucleon energy. Secondary, our helium intensity is nearly half of those given by JACEE and SOKOL,while consistent with MUBEE. Therefore, the slopes of our proton and the helium spectra are nearly parallel,with indices of 2.74  0.08 and 2.78  0.20 in the energy range less than 100 TeV/nucleon, respectively, wherethe errors are statistical only.In order to see the later result more distinctly, we show the energy dependence of the helium-to-proton fluxratio over the very wide energy range 500 MeV/nucleon to 100 TeV/nucleon in Figure 2. A discrepancy inthe lower energy region, ﬀ 10 GeV/nucleon, is apparent between AMS, BESS and IMAX, but this is simplydue to the different period in the solar activity of each experiment. The change in the ratio at lower energies,ﬀ 10 GeV/nucleon, may be due to the re-acceleration effect, which must be significant for lighter elementssuch as protons and helium which have much longer collision mean free path than the escape length from theGalaxy, whereas it would not be so important for heavier elements [1].It is clear that the RUNJOB plots lie on the extrapolation from those in the lower energy data with a constantvalue  0.05, while the JACEE [16] data suggest the ratio increases gradually with energy, reaching  0.15at 100 TeV/nucleon. The RUNJOB result seems to match the current understanding of the shock accelerationmechanism in supernova remnant which depends only on the particle rigidity, while the JACEE result areunexpected from these expectations. So the discrepancy between JACEE/SOKOL and RUNJOB/MUBEE isp and He spectra by RUNJOB 1910110210310410510-1 100 101 102 103 104 105 106IMAXAMSBESS ATIC1MUBEESOKOLJACEERUNJOB (this work)E02.75  dI/dE0 [m-2sr-1sec-1 GeV/n1.5 ]kinetic energy E0 [GeV/nucleon]protonheliumFigure 1. Proton and Helium spectra obtained by full data of RUNJOB experiment(open and lled circle) together withother direct observations[9, 10, 11, 12, 13, 14, 15].critical for our understanding of the origin of CR and the acceleration mechanism, with these two sets of resultsleading to quite different alternatives.3. ConclusionThe proton and the helium spectra and thier ratio, helium/proton, were presented in this report that basedon full data in the energy range between 10 and 500 TeV/nucleon observed by RUNJOB experiment. Theboth spectra are almost palarell with power index of  2.75 and the ratio is constant with value  0.05 lyingon the extrapolation line from those in the lower enegies. Moreover we observed a proton with PeV energydirectly. These results suggest the acceleration and propagation process of CRs depend on its rigidity, thoughthe statistics more than 100 TeV/nucelon is not enough to discuss the acceleration limit by supernovae. Infuture, we need some direct observations in the energy range between 10ﬂﬁand 10ﬃto clear the accelerationlimit connecting “knee” problem.AcknowledgmentsThis work has been supported by Institute of Cosmic Ray Research (ICRR), University of Tokyo, Instituteof Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Grants-in-Aid forScientific Research and also for International Scientific Research from Japan Society of Promotion of Sciences(JSPS) (grant no. 08404012, 08045019 and 111695026), and Russian Foundation of Fundamental Research(grant no. 00-15-96632), International Projects of Russian Ministry of Science and Technology, and Russian20 M. Hareyama et al.10-210-110010-1 100 101 102 103 104 105 106IMAXAMSBESSJACEERUNJOB (this work)helium/protn ratiokinetic energy E0 [GeV/n]Figure 2. The ratio of proton to helium uxes obtained by full data of RUNJOB experiment(lled circle) with other directmeasurements as AMS, BESS, IMAX and JACEE[16]. The AMS , BESS and IMAX data are cluculated by one of authors,M.H, from thier papers [12, 13, 14, 15].Commission of Balloon Research, Grants PFFI 99-02-1772, 99-02-31005, 99-02-18173, Grant  UniversitetiRossii” 990592 in Russia.References[1] Seo, E.S. and Ptuskin, V.S., 1994, ApJ, 431, 705[2] Ellison, D.C., Drury, L.O’C., & Mayer, J.P. 1997, ApJ, 487, 197[3] Apanasenko, A.V., et al. 2001, Astropart. Phys., 16, 13[4] Furukawa, M. et al., 2003, Proc. 28th Int. Cosmic Ray Conf. (Tsukuba), 4, 1837[5] Hareyama, M., et al. 2003, Nucl. Instr. & Methods A, 512, 571[6] Ichimura M. et al. for RUNJOB collaboration, to appeare in this proceedings[7] Sveshnikova L.G. et al. in RUNJOB collaboration, to appear in this proceedings[8] Debina V.A. et al., ApJL, in press[9] Asakimori, K., et al. 1998, ApJ, 502, 278[10] Ivanenko, I.P., et al. 1993, Proc. 23rd Int. Cosmic Ray Conf. (Calgary), 2, 17[11] Zatsepin, V.I., et al. 1994, Yad. Fiz. 57, 684[12] Alcaraz, J. et al. 2000a, Phys. Lett. B, 490, 27[13] Alcaraz, J. et al. 2000b, Phys. Lett. B, 494, 193[14] Haino, S., et al. 2004, Phys. Lett. B, 545, 1135[15] Menn W. et al. 2000, ApJ, 533, 281[16] Asakimori, K., et al. 1993, Proc. 23th Int. Cosmic Ray Conf., (Calgary), 2, 25

Proton and Helium spectra obtained by RUNJOB experiment

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