1. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 1 CEX beam test at piE1 Satoshi Mihara

2. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 2 Elementary process  - (essentially) at rest captured on protons:  - p   0 n  - p  n   0    Photon spectru m 54.982.9 129 MeV M  /2  M  /2(1  cos  * ) M  /2 ** E  =55 MeV   * = 

3. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 3 Angular selection  - p   0 n  0 (28MeV/c)    MeV  eV Requiring   FWHM = 1.3 MeV Requiring  > 175 o FWHM = 0.3 MeV   170 o 175 o 00     54.9MeV82.9MeV 1.3MeV for  >170 o 0.3MeV for  >175 o

4. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 4 Overview of the beam test 25/Sep Detector was moved to the area. evacuation 27/Sep- Beam tuning 29/Sep pre-cooling 2/Oct-5/Oct Liquefaction 5/Oct-29/Oct Purification(gas phase) 5/Oct- Electronics setup 15/Oct  0 detected 24/Oct empty target run 1/Dec PMT amplifier study 6/Dec Recovery 7/Dec Cold xenon gas data for PMT calibration 22/Sep 29/Sep 6/Oct 13/Oct 20/Oct 27/Oct 3/Nov 10/Nov 17/Nov 24/Nov 1/Dec 8/Dec  0 detected Beam tuning purification pumping Cooling/liquefaction DAQ ~7weeks Recovery Cold xenon gas data

5. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 5 Beam line –Magic momentum (110MeV/c) –FSH52, 4mm carbon degrader (110  107MeV/c) in ASY51 –26mm carbon degrader in front of the target –S1 counter (40x40x5mm3) to define the beam Area layout –The Electronics barrack placed in the area with concrete shielding around it. –All controls and monitors done in the barrack. –Liquid nitrogen supplied from a dewar located in the area.  E1 beam line Proton beam Target ASY51

6. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 6 Setup Carbon degrader

7. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 7 Hydrogen Target Thanks to Dr. J. Zmeskal. Liquid H2 cooled with a GM-refrigerator Temperature control Target cell –0.5mm t Al –40mm d x 100 L –125cc liquid hydrogen Kapton foil –  entrance –  exit   

8. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 8 NaI detector For tagging  at the opposite side of LP 8x8 NaI crystals –40.6x6.3x6.3cm 3 Located 110cm from the target Signal processor and Trigger Box (QUAD module) to provide trigger signal ABCDEFGHABCDEFGH 8 7 6 5 4 3 2 1 For trigger Base Line Stabilizer Attenuator x10 ADC Trigger Box TDC Crystal Array HV Trigger module Differential input stage Differentiator, Attenuator and base line stabilizer Output stage

9. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 9 Timing Counter 2 layers of –5cm x 5cm x 1cm BC404 –Hamamatsu R5505 at both ends –3mm t Pb plate 40% efficiency for 83MeV  Time resolution can be estimated internally. 5cm x 5cm x 1cm t BC404  R5505 Viewed from the target 100mm  Lead collimator TC LP NaI  S1 TC t LP - t TC

10. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 10 Xenon Large Prototype operating condition Gain/QE calibration –LED and  as usual Absorption length after 2 weeks purification abs > 140cm (90% C.L.) (central value ~2.7m) Xenon extracted from the chamber is purified by passing through the getter. Purified xenon is returned to the chamber and liquefied again. Circulation speed 5-6cc/minute

11. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 11 Data Acquisition Hardware setup –ADC 3 ranges for front-face PMTs –TDC for all PMTs –PMT amplifier (x10) BINP Lecce Software –Online MIDAS –Slow control (MSCB+LabView) Refrigerator control, Temp., Pressure Monitor Data set –Collimators in front of LP and NaI (  back to back) –Timing Counter (Pb+Scintillator) in front of NaI

12. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 12 Trigger back-to-back  data –NaI : sum signal of the central 4 crystals –LP: sum signal of 8 PMTs on the front face & 4 PMTs on the back face  data with opening angle < 180 o –NaI : QUAD module Very low threshold trigger for LP –One or two hit(s) in any one of 8 clusters , LED, cosmic-ray, pedestal triggers for calibration

13. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 13 Beam Condition p(  - )=107MeV/c –Almost maximum separation (8nsec) of arrival time to the target between  and , and between  and e. Beam intensity –Up to 2.6 MHz @ 1800  A Electron contamination in the beam –Negligible in triggered events target  x=12mm  y=12mm  e ~8nsec

14. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 14  0 signal example LP ADC NaI ADC LP 83 MeV  NaI 55 MeV  LP 55 MeV  NaI 83 MeV 

15. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 15 Background Condition Beam on/off –PMT output for  events changes, reduced to 70% of normal values Not due to bleeder current because we can see the effect even with lower PMT gain. Background events –most probably caused by beam- related neutrons, –Energy deposit up to 9-10MeV –Corresponding to 1.5x10 6 pe/sec cause this deterioration.

16. Satoshi Mihara ICEPP, Univ. of Tokyo Feb. 2004 MEG Review Meeting 16 CEX beam test –NaI analysis  Toshiyuki –Xenon Large Prototype Analysis  Ryu, Fabrizio, and … –Stability monitor  … PMT studies  Yasuko and Alessandro TERAS beam test –TERAS analysis Update  Kenji Final Detector –Cryostat  Fabrizio R. –Refrigerator  Tom –Liquid phase purification  Satoshi