meeting minutes

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

Report on the last liquefaction test:

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

No PMT signal distortion could not be seen during the refregirator operation. No signal distortions also during operation of the vacuum pump for the outer vessel.
"additional ref. power" was estimated as the heater power on the cold head to controll the temperature. The difference between two conditions is close to that of the design values.
The ref. power for xenon temperature stabilization should not exceed that in vacuum.

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

Design and construction of the vessel:

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.

Assignment of responsible persons to each part:

S. Mihara, Dec 5th, 2000