Photon Detector Meeting
10/May/2001
@KEK
written by SM



A.Maki, T.Haruyama, S.Suzuki, T.Mori, T.Mashimo, S.Mihara, W.Ootani, K.Terasawa, K.Ozone, H.Nishiguchi, M.Yamashita, R.Sawada, T.Ishida, Mitsuhashi, Yoshimura Results of the last liquefaction test of ~100L xenon at KEK was reported by T.Haruyama. The following table shows amount of used LN2 and days during this test together with a prediction for the case of the final photon detector.
 
 
Large Prototype
(This test, 100L)
days          LN2
Large Prototype
(This test, 100L)
days          LN2
comment
vacuum pumping 16 days      --- ---           ---
pre cooling 1 day         425L 4 days        1700L 0.2MPa xenon
supposing *4 cold mass
liquefaction 2.3 days     375L 18 days     6750L In case the same liq. rate(2.0L/H)
DAQ 2.5 days     --- ---          --- refrigerator operation
recover 2 days       600L 16 days     4800L In case of the same rec rate(2.6L/H)

Liquefaction and recovering rate of xenon was 2.0L/hour and 2.6L/hour respectively. These rate could be limited by the size of the gas transferring pipes/valves and would be increased by modifying the transfer line in the final detector.

He reported also about the measurement of heat income to the vessel at liquid xenon temperature. The result is summarized in the following table.
 

Condition Design value from xe evaporatin rate(A) additional ref. power(B) expected ref. power(A+B) Ref. power measured in vacuum from pressure increasing rate
PMT HV ON
40W
(Vessel 20W
PMT 15W
Cables 5W)
39W
(2.5 H later)
20W
59W
65W
---
PMT HV OFF
25W
(Vessel 20W
PMT 0W
Cables 5W)
34W
(1 H later)
33W
67W
65W
---
status External gas flow.
Pressure stable
@162K
Closed.
stand-alone test data analysis going
REMARK


He showed a note describing the items that have to be controlled and monitored during the final detector operation. They will be taken into accout in the design of the slow controll system
 

Discussion was done concerning the general policy how to proceed the design and construction works.
  • Design work should be completed in this Japanese fysical year (-Mar 2002)
  • Construction will be started at the beginning of the next fysical year.
  • By the end of this month, SM will prepare a plan for design work and summarize important parameters.
  • This plan will be shown to several manufacturers in June and ask them to give us a cost estimate for the design work.
  • Decision will be done in this summar and we will ask the manufacturer to start immediately.
  • It is very important to tell manufacturers that the design work is seperated from construction, that is, we will not nesessarily ask the construction work to the same manufacturer to whom we ask the desing work.

  • MEG Home Page
    S. Mihara, Dec 5th, 2000