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Status Report for KEK-PS E391a. KEK IPNS G.Y.Lim 14 April 2003. Measurement of BR( K L p 0 nn ). Collaboration High Energy Accelerator Research Organization, KEK Faculty of Science and Engineering, Saga University Department of Physics, Yamagata University
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Status Report for KEK-PS E391a KEK IPNS G.Y.Lim 14 April 2003
Measurement of BR( KLp0nn ) Collaboration High Energy Accelerator Research Organization, KEK Faculty of Science and Engineering, Saga University Department of Physics, Yamagata University Department of Physics, Osaka University Research Center for Nuclear Physics, Osaka University National Defense Academy of Japan Joint Institute for Nuclear Research (Dubna) Russia Department of Physics, University of Chicago, USA Fermi National Accelerator Laboratory, USA Department of Physics, Pusan National University, KOREA E391a experiment • Two-step program (KEK-PSJPARC) • From the E391a • Establish measurement principle • Search for near SM expectation Data taking from Feb. 2004 • Engineering run • Preparation of detector components New KEK member Department of Physics, Kyoto University
Middle Section Downstream section Upstream section E391a Detector Engineering Run on last winter
Fabricate on last summer Engineering Run • DAQ using self-trigger of CsI Same scheme of real run Tuning / feed-back • CsI calibration • Cosmic test in vacuum chamber • Cosmic test during stacking • Punch-through muon • Two gammas from single p0 • Multi-gamma decay (Kpi2, Kpi3) • KL decay data – same format of real run • Develop on-line/off-line software Significant step to the successful experiment
Distributed and parallel processing LeCroy 1885N FASTBUS ADC TKO HR-TDC Operation with tiny noise 1mV threshold for TDC ( 1 MeV) 50 fC ADC pedestal (0.1 MeV) DAQ with low noise level
Using cosmic rays Using punch-through muons pQ/cm pQ MeV/pQ CsI ID CsI ID Calibration using cosmic/punch-through muon Good agreement between two gain factors !
Two g invariant mass (MeV/c2 ) Before correction After correction Reconstructed position(cm) p0 n Two g invariant mass (MeV/c2 ) sm : 5.4 MeV/c 3.7 MeV/c Incident position (cm) 2 2 Incident position (cm) p0 Calibration using p0-production
Radial hit distribution of gamma Vertex along the beam direction Study using Kpi3 decay Background free without veto system Comparison with M.C. - Good agreement Calibration method in real run How to get correct energy scale Detailed study is going on
Inner CsI • Short spill beam (1X1012 ppp/ 200 ms) • Single counting rates (10 mV Thres.) CC03 Ratio of on/off spill for Xe-peak Xe signal of the 1st CsI module 1.05 Counts / SEC Off spill On spill Normalize counts Outer CsI 1.0 KTeV CsI Peak=1437 s/Mean=1.6% 0.95 CsI ID ADC channels Response at the high Intensity • PMT gain(Xe monitoring system) Same performance under the high beam intensity 7.0 X 1011 / 2s 1.4 X 1012 /2s 1.0 X 1012 / 0.2s
Cosmic test is going on Assembling jigs are being fabricated - KEK machine shop No. of p.e. / MeV Distance from the PMT (cm) Detector fabrication – Upstream Modules/vacuum chamber done Assembling on June -July
Vacuum Chamber : Start bidding process arrive at the end of Oct. Detector fabrication – Middle Fabrication of 3 modules ー Finished 1 module/1 week End of Oct. (32 modules) Design of assembling jigs – final stage Assembling Nov. – Dec.
Front barrel Design Front barrel Construction Assembling Upstream section Central barrel Design Main barrel Construction Vacuum & Cosmic Test CsI Assembling Evacuating Test Assembling Detector setup Beam survey Engineering Run Data Taking Cosmic Run Cosmic Run Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. 2001 2002 2003 2004 Up-dated on April, 2003 Schedule
Summary • E391a is aiming for measuring the BR( KLp0nn ) • Realizing Step-by-step • Engineering run • Stable data taking using same triggering scheme of real run • CsI calibration – cosmic ray data is very nice input • No problem at high beam intensity • Good agreement with M.C. • Detailed study is going on • E391a is preparing almost on schedule • Downstream section is polishing stage • Upstream/middle section – being fabricated smoothly • Prompt start at the real run (Feb. – June, 2004) - Full beam acceptable