1993 Fiscal Year Final Research Report Summary
Liquid Xe Homogeneous Shower Calorimeter with Excellent Energy Resolution in the GeV Region
| Project/Area Number |
03554005
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | Waseda University |
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Principal Investigator |
DOKE Tadayoshi Waseda University, Advanced research Institute for Science and Engineering, Professor, 理工学総合研究センター, 名誉教授 (60063369)
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| Co-Investigator(Kenkyū-buntansha) |
KASAHARA Katsumasa Shibaura Institute of Technology, Faculty of System Engineering, Professor, 工学部, 教授 (00013425)
SHIBAMURA Eido Saitama Coolege of Health, Professor, 理工学総合研究センター, 客員研究員 (30100605)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Liquid Xe / Homogeneous ionization calorimeter / GeV region / High energy resolution / Electro-magnetic shower |
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| Research Abstract |
Since 1970's, liquid Ar has been used as detection medium for electro-magnetic shower calorimeter but it has been used only as sampling calorimeter with thick converter electrodes like iron or lead to make its size compact. Therefore, the energy resolution could not achieve an excellent energy resolution as expected in the recent elementary particle experiments. If the calorimeter is used as homogeneous calorimeter in which the electrode system consists of very thin electrodes, it is expected that an excellent energy resolution of the order of 0.1% for high energy electrons can easily be realized. From such a view-point, in the middle of 1990's, liquid Kr homogeneous calorimeters have constructed in CERN and Novosibirsk for elementary particle experiments. To make calorimeter more compact, the use of liquid Xe in place of liquid Kr was hoped. Several researchers constructed prototype liquid Xe calorimeters and tested them. However, they could not achieve excellent energy resolution bec
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ause of miss design of the calorimeter or use of non-pure liquid Xe. We constructed a new liquid Xe homogenous calorimeter in 1992 and at first tested using liquid Ar in place of liquid Xe. We needed three years for getting a large amount of Xe gas. As a result, we could make the first test of our liquid Xe calorimeter at CERN in 1995. Unfortunately, in the test, we could not observe any ionization signals from the calorimeter. After some improvement of the electrode system in the calorimeter, the second test was made at CERN in 1996. The second test was successfully achieved except that the signals from the fifth readout could not be observed because the lead wire from the electrode was shorted to the ground. The results of the test for 70 GeV electrons are given as follows.
The energy resolution (experiment) 2.06%
The energy resolution (experiment) after correction for the 5^<th> reabout 0.96%
The energy resolution (experiment) after subtraction of electron beam 0.71%
momentum spread (0.65%)
The energy resolution (Monte Carlo sumulation) 0.32%
not including the electron beam momentum spread (0.65%)
As seen from this table, the correction was made by using the energy loss in the 5^<th> reabout which was obtained by fitting to the build up curve for each event was not successful. By applying the same correction method to the result obtained by the MonteCarlo sumulation, we found that there is a good reverse correlation between the energy loss in the 5^<th> readout and the total energy loss other than the contribution from the 5th readout and the fluctuation in the correlation is much better than that for the contribution from the 5^<th> readout obtained after the correction. This shows that the correction obtained from the fitting to the observed build up curve for each event should be more modified according to the reverse correlation. At present, we are investigating about how to modify our correction under the above fact. Less
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