MINUTES OF E362 FRONT DETECTOR MEETING Date: 15:00-18:00, December 6, 1995 Place: KEK R307 Present: Nishikawa (Chairman), Ishii, Chikamatsu, Miyamoto (INS), Miyano, Nakamura(Niigata), Tamura(Okayama), Aoki, SuzukiAT, Kohama(Kobe), Ohyama, Sakuda(KEK), Etou(Toukai), Y. Itow(ICRR) ----Distributed to -------- KEKVAX::NISHIKAW, KEKVAX::CHIKAMAT, kekux::"miyamoto@ieux01.ins.u-tokyo.ac.jp", kekvax::kenzo, KEKVAX::SAKUDA, kekvax::kanzaki, KEKVAX::OYAMAY, KEKVAX::SOSAMU, KEKVAX::MINORU, KEKPSA::ieiri, KEKUX::"miyano@ngthep.hep.sc.niigata-u.ac.jp", kekvax::tamuran, KEKUX::"SOBEL@MASTER.PS.UCI.EDU", kekvax::gajewski, kekux::"chiaki@sbhep.physics.sunysb.edu", kekvax::suzukia, kekux::"totsuka@jpnutins.bitnet", kekux::"suzuki@icrkm4.icrr.u-tokyo.ac.jp", kekux::"koshio@icrr.u-tokyo.ac.jp", kekux::"masato@icrkm4.icrr.u-tokyo.ac.jp", kekux::"itow@suketto.icrr.u-tokyo.ac.jp", kekux::"sakai@icrr.u-tokyo.ac.jp", kekux::"kajita@icrr.u-tokyo.ac.jp", kekux::"nakahata@icrr.u-tokyo.ac.jp", kekux::"koshio@icrr.u-tokyo.ac.jp", kekux::"inoue@icrkm4.icrr.u-tokyo.ac.jp", kekux::"kaneyuki@phys.titech.ac.jp", kekux::"thara@kobe-u.ac.jp", kekux::"aoki@kobe-u.ac.jp", KEKUX::"SUZUKI@PHYS01.PHYS.KOBE-U.AC.JP", KEKVAX::NIWA, kekvax::asai, kekux::"kyosi@tkikam.sp.u-tokai.ac.jp", kekux::"masayuki@tkikam.sp.u-tokai.ac.jp", kekux::"alpinist@sbhep.physics.sunysb.edu", kekux::"jimhill@sksol1.physics.sunysb.edu" -------------------------- (1) Beam Monitor Nishikawa explains the 1/r**2 problem of the neutrino beam. He proposes to use the muon ranger of the front detector (L=300m ) as the beam profile monitor with respect to r=0-4m. The number of muons from CC process is about 2x10**4/ton/10**20POT. One muon filter (8mx8mx0.1m) weighs 50tons and the event rate is good enough. Showing that the beam Monte Carlo agrees with the measured yield wrt r=1,2,3,4m will give another confidence of the beam MC. Design for the detector hall will be finished by next summer. Thus, the simulation study for 1kton tank detector must be finished by then. For that study, we desparately need a 1-ring reconstruction program. (2) Simulation Chikamatsu summarizes what was discussed at SK meeting (Atm-nu,Kajita) on 12/4: Y. Suzuki stressed that it is important to measure the ratio of NC(pi0)/CC(mu) with the front detector (either water-tank or fine grain); it will improve the Super-K analysis of atmospheric neutrinos. ->Chikamatsu volunteers the analysis of 1kton water-tank detector. He shows the result of the GEANT simulation on the muon ranger. If he requires at least one hit in the muon chamber, the muon energy resolution is good (~5%) for E_mu=0.5-3.5 GeV, but the efficiency is low (20%) at E_mu=0.5 GeV. If he allows muons to stop in LG, the efficiency recovers (70%), but the muon energy resolution gets worse for E_mu<1 GeV (~20% at 0.5 GeV). The goal is to find a solution to use less muon chambers and iron filters and have a good sensitivity to neutrino oscillations. Suzuki-AT continues the work on the optimization of the muon chambers (See his memo on Nov10). He will also study the possibility of using the muon ranger as the beam profile monitor, which Nishikawa proposed in (1). Itow points out that when muons stop in LG, they cannot be distingushed from pions. He is right. However, we require a good track (>20cm) in SCIFI. Pions tend to interact in water. We will check S/N in MC. (3) SCIFI hardware Etou reports the measurement of the light yield and attenuation length of the 3m long fiber (0.5mmD,0.7mmD,0.9mmD, SCSF78,single clad) at Nagoya on 12/4 [Etou,Nishijima,Aoki,SuzukiAT,Ohyama,Nakamura,Iinuma,Sakuda]. Results are consistent with each other considering the diameter: 0.5mmD 0.7mmD 0.9mmD PE(photo-electrons) at L=1m 2.6 4.3 6.0 PE with glue (at L=1m) 2.3 3.7 --- Attenuation length 3.1m 3.1m 3.5m (See his memo for details) The above results were obtained by the on-line program. He will re-analyze the data and obtain more accurate values with error bars. He will also estimate the efficiency for the case of 2 layers using the measured PE yield. In the measurement, the far end of the fiber is unmirrored. If the far end is mirrored as Nagoya group does (reflection efficiency=0.8), the effective attenuation length for 4m long fiber is estimated to be 6m. (4) SCIFI readout Aoki lectures on Image Intensifier readout system: Invertertype, Adjacent type, Static-type, MCP etc..(A copy of his transparency is available) He then proposes 3 types for our application. (a) 100mmD-II + 3 static-type + CCD (b) 100mmD-II + 1 MCP + lenz + CCD (c) 100mmD-II + 1 MCP + tapered-fiber + CCD (a) seems too expensive. Tapered-fiber (c) is better than lenz (b). If the gain is not eneough, 1 MCP is added to (b) or (c) as UA2 or E244. Choice of the first MCP is restricted by the Hamamatsu 100mmD-II. Aoki will negotiate with Hamamatsu this week. We will start with (b) or (c). He also shows the broad pulse-height distribution for 1 PE (LED) when seen by 100mmD-II. The pulse height has a peak at about 20ch, but extends up to 80ch. So, it will be hard to separate MIP (mu or pi, 2PE/fiber) from protons (10PE/fiber). This can be tested next year using beta-source or LED. Itow comments that dE/dx can be achieved by using PMT's seeing the signal on one end of the fiber. ->However, in this case the fiber length gets longer while the attenuation length is 3m instead of 6m (mirrored). We will order a set of Fibers, II, MCP and Power supply within a week or so. (5) SCIFI structure Nakamura (Nagoya) says that he will make a sample of fiber sheets for us this month. He also proposes to use a honeycomb with G10 skin to construct water/SCIFI detector. He had a honeycomb sample made at a company nearby. Sakuda shows a paper model of Al-honeycomb on which a set of fiber sheets is glued. Fiber sheet will be covered by Mylar sheets. When a sample sheet is given by Nagoya, we (Nakamura and Sakuda) will talk to KEK mechanical engineering center to discuss the mechanical design. (6) NC(pi0)/CC ratio Nakamura-T(Niigata) will study electron identification with the fine-grain detector using GEANT: (a) nu_e/nu_mu ratio measurement, and (b) NC(pi0)/CC. Itow says that Miura(ICRR) will work on this too. He transferred the GEANT simulation to ICRR workstation. (7) Carbon or Oxygen Kaneyuki (TIT) kindly sent us a program for quasi-elastic interaction with Pauli-suppression effects where the cut value for Fermi-momentum can be changed. Besides this effect, pion absorption probability may be different. It is nice that we understand the difference quantitatively. ->Nishikawa proposes Next meeting on December 20 or 21, + Party. (Memo by Sakuda)