Ichimura, M

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29th International Cosmic Ray Conference Pune (2005) 3, 2124Heavy component spectra and secondary to primary ratios obtained byRUNJOB experimentM. Ichimura , V.A.Derbina, V.I. Galkin, M. Hareyama, Y. Hirakawa , Y. Horiuchi,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)(a) Physical Department of Moscow State University, Moscow 119899, Russia(b) D.V. Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119899, Russia(c) Major in Pure and Applied Physics, Science and Engineering, Waseda University, Tokyo 169-8555, Japan(d) Faculty of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan(e) Department of Physics and Mathematics, Aoyama Gakuin University, Tokyo 157-8572, Japan(f) Multimedia Information Research Division, National Institute of Informatics, The Ministry of Education,Tokyo 101-8430, Japan(g) School of Medicine, Hirosaki University, Hirosaki 036-8562, Japan(h) P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow 117924, Russia(i) Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara 229-8510, Japan(j) Faculty of Comprehensive Welfare, Urawa University, Urawa 336-0974, Japan(k) Shonan Institute of Technology, Fujisawa 251-8511, JapanPresenter: M. Ichimura (ichimu@cc.hirosaki-u.ac.jp), jap-ichimura-M-abs1-og11-oralRUNJOB final results on the energy spectra of primary heavy cosmic ray components are presented. Data arefrom ten RUNJOB campaigns performed from 1995 through 1999. And the energy spectra of CNO, NeMgSiand Fe groups are shown here as well as the energy dependence of the secondary/primary ratio.We find our heavy component spectra are in agreement with the extrapolation from those at lower energiesobtained by CRN (Chicago group), monotonically decreasing with energy, in contrast to JACEE and SOKOLdata, which indicated a gradual increase with energy, particularly for the CNO group at 5 TeV/nucleon.As for the secondary to primary ratio we have observed in TeV/nucleon energy region, it is difficult to determinethe energy dependence of their average path lengths by the RUNJOB data only, because the large uncertaintyof atmospheric corrections due to the poor statistics exists.1. IntroductionHeavy primaries in cosmic rays provide us additional informations to those from protons and alpha primaries.Heavy components of cosmic rays are created in the thermonuclear fusion process in the star, though protonsand helium nuclei were produced at the beginning of the universe. So heavy components carry more informa-tions on the origin of cosmic rays. Moreover, the nuclei which are not created in the star tells us the galacticspace through which the cosmic rays propagate. To analyze the propagation of cosmic rays, the leaky boxmodel with the energy dependent escape length has been often used, but it would be unrealistic in the higher22 M. Ichimura et al.energy region. So observation at the higher energy region is essential to check the models of the propagations.RUNJOB data is important to infer the propagation models, though statistics is still poor.2. Results and DiscussionWe give the energy spectra of the three heavy-primary groups, CNO, NeMgSi, and Fe, in Figure 1, where thefilled red symbols denote RUNJOB data, and other data, HEAO-3[1], SANRIKU[2], CRN[3],[4], SOKOL[5]and JACEE[6] are also plotted. The vertical axis is multiplied by   . One should remember here that theJACEE data for iron include the sub-iron components with ﬁﬀﬃﬂ  , while those from RUNJOB are forpure iron only.10-310-210-1100101102103100 102 104 106HEAO-3SANRIKUCRNSOKOLJACEERUNJOB(this work)E02.5 dI/dE0 [m-2sr-1sec-1 GeV/n1.5 ]kinetic energy E0 [GeV/nucleon]CNOiron (x1/100)NeMgSi (x1/10)Figure 1. Heavy component spectra obtained by RUNJOB (lled red) together with other direct measurements. Theintensities are multiplied by 1/10 for the NeMgSi-group and 1/100 for the iron-group, respectively.The RUNJOB data appear to be consistent with the extrapolation of CRN data in the lower energy region,Heavy component spectra and ... 23whereas the JACEE and SOKOL data seem to increase gradually in the higher energy region, particularly forthe CNO group.Taking the data of RUNJOB and CRN alone, the energy spectra of heavy components decrease monotonicallywith energy up to  10 TeV/nucleon, and the slope of the energy spectrum becomes gradually harder withheavier mass, for instance  2.7 for the CNO group and  2.6 for Fe. The paper of p-He spectra by RUNJOBin this proceedings shows that the slope of proton and helium spectra is ﬂ"!#  ﬂ$! % . Thus the gradual change inthe slope of the energy spectra of the individual elements indicates a rigidity-dependent form. This result is anatural consequence of the different collision cross-sections, with, for instance,  40 mb for p–p and  750 mbfor Fe–p in the TeV region. This could be explained by the following possible scenarios; the stochastic shockacceleration at supernova blast waves, and the leakage from the Galaxy in the propagation process, both ofwhich depend on the particle rigidity [7].On the other hand, if JACEE and SOKOL data are true, we must find an alternative scenario, in relation to thesource and the acceleration mechanism. In fact, as several authors have pointed out, based on JACEE data thesource of helium and heavier components must be different from that of protons, and could, for example, beproduced by supernova shocks expanding into Wolf-Rayet winds [8], [9], [10].In Figure 2, we show the secondary/primary ratio obtained by the present work together with other data,ACE/CRIS[11], HEAO-3[12], [1] and SANRIKU[13], covering the lower energy region. One should recall,however, that the balloon altitude in RUNJOB of  10 g/cm  results in a considerable contamination effect forthese secondary components, coming from the fragmentation products in the atmosphere. We have eliminatedcontaminations of 45% for the sub-Fe components and 67% for the LiBeB group in Figure 2, with the detailsof these calculations appearing in the reference [14], which summarizes the simulation procedure and explicitvalues of the fragmentation parameter for various projectile nuclei in the atmosphere. So the RUNJOB data inFigure 2 need to be viewed with these uncertainties in mind, and we reserve a definite conclusion for the futurestudy.3. ConclusionWe have discussed the spectra of heavy components, combining the data from RUNJOB and CRN, but it isapparent to require the single experiment to cover this energy region with suitable statistics.Admitting the poor statistics and the uncertainty of atmospheric corrections, we would point out that ourRUNJOB observations of 2ry/1ry ratio may not lie on the extrapolation of the lower energy data. It indicatesthe simple leaky box model with the decreasing escape length for the rigidity may not work in higher energyregion. More certain data is required to draw the definite conclusion as said before.4. AcknowledgementsThis 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 RussianCommission of Balloon Research, Grants PFFI 99-02-1772, 99-02-31005, 99-02-18173, Grant & UniversitetiRossii” 990592 in Russia.24 M. Ichimura et al.10-310-210-110-1 100 101 102 103 104ACE/CRISHEAO-3SANRIKURUNJOB(this work)secondary/primary ratiokinetic energy E0 [GeV/nucleon](a) Boron/Carbon(b) [Sc+Ti+V]/iron      (x1/10)[Li+Be+B]/[C+N+O]             for RUNJOBFigure 2. Secondary to primary ratios for (a) B/C and (b) sub-Fe/Fe, where RUNJOB data give [LiBeB]/[CNO] in placeof B/C, and sub-Fe represents ')(+*-,/.0*1 .References[1] Engelmann J.J., et al., A&A., 233(1990)96.[2] E. Kamioka et al., 1997, Astropart. Phys., 6, 155.[3] Mu¨ller D., et al., 1991, ApJ., 374, 356.[4] Swordy S.P., et al., 1993, ApJ., 403, 685[5] Ivanenko, I.P., et al. 1993, Proc. 23rd Int. Cosmic Ray Conf. (Calgary), 2, 17[6] Asakimori, K., et al. 1997, Proc. 25th Int. Cosmic Ray Conf., (Durban), 2, 1[7] Shibata, T., et al. 2004, ApJ, 612, 238[8] Biermann P.L. 1993, A&A, 271, 649[9] Biermann P.L. & Strom, R.G. 1993, A&A, 275, 659[10] Biermann P.L., Gaisser, T.K., & Stanev T. 1995, Phys. Rev. D, 51, 3450[11] Davis A.J., et al., AIP Conf. Proc., 528(2000)421.[12] Binns W.R., et al., 1988, ApJ., 324, 1106.[13] Hareyama M., et al., 1999, Proc. 26th Int. Cosmic Ray Conf. (Salt Lake City), 3, 105.[14] Ichimura M., et al., 1993, Phys. Rev., D, 48, 1949

Heavy component spectra and secondary to primary ratios obtained by RUNJOB experiment

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