| Project/Area Number |
20340058
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Waseda University |
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Principal Investigator |
KASAHARA Katsuaki Waseda University, 理工学術院, 教授 (00013425)
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| Co-Investigator(Renkei-kenkyūsha) |
TORII Shoji 早稲田大学, 理工学術院, 教授 (90167536)
OZAWA Shunsuke 早稲田大学, 理工学術院, 講師 (60506715)
SHIMIZU Yuuki 早稲田大学, 理工学術院, 講師 (60434320)
MASUDA Kimiaki 名古屋大学, 太陽地球環境研究所, 准教授 (40173744)
SAKO Takashi 名古屋大学, 太陽地球環境研究所, 助教 (90324368)
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| Project Period (FY) |
2008 – 2010
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| Project Status |
Completed (Fiscal Year 2010)
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| Budget Amount *help |
¥18,980,000 (Direct Cost: ¥14,600,000、Indirect Cost: ¥4,380,000)
Fiscal Year 2010: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2009: ¥7,150,000 (Direct Cost: ¥5,500,000、Indirect Cost: ¥1,650,000)
Fiscal Year 2008: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000)
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| Keywords | 超高エネルギー宇宙線 / LHC加速器 / ハドロン相互作用 / モンテカルロ / 空気シャワー / 宇宙物理 / GZKカットオフ / CERN LHC / 多重発生 / 各相互作用モデル |
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| Research Abstract |
LHCf is a dedicated experiment to observe the spectrum of photons and neutrons produced in the very forward region of collisions at CERN LHC of which energy is comparable to the ultra-high energy cosmic rays (UHECR). The purpose is to validate nuclear interaction models used in the Monte-Carlo (MC) simulations for cosmic-ray experiments, and thus to help clarify the mystery of UHECR.
LHCf successfully observed the 450 GeV+450 GeV collisions in the end of 2009 and also 3.5 TeV+3.5 TeV collisions in 2010. The energy is equivalent to the laboratory energy of 4.3・10^<14> eV and 2.6・10^<16> eV, respectively. We examined MC models, DPMJET(v3.04), PYTHIA(v8.145), QGSJET II(v03), SIBYLL(v2.1) and EPOS(v1.99). The spectrum in this completely unexplored region was found not completely far way from our expectation, but these models cannot fit the experimental data in a satisfactory way. The photon spectrum is softer than many MC models while hadrons show a harder spectrum. If we consider the pseudo-rapidity (η) distribution in the central region, obtained by other LHC experiments (ATLAS and CMS), together with our data, we may say all interaction models breakdown in the LHC energy region. DPMJET is a very good model in the low energy region but its photon spectrum is much harder than the LHCf data and theηdistribution suddenly breakdowns at LHC energies. PYTHIA, though tuned to fit the LHCηdistribution, shows a similar photon spectrum as DPMJET.
These facts indicate that we need to explore the highest energy LHC collisions expected in a few years to clarify the breakdown tendency and to validate the models, and also that it is important to construct a new interaction model.
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