Report of Chinese muon ID tubes

Report of Chinese Muon ID Tubes

Y. Nakada, H. Enyo and K. Imai
Kyoto University, Kyoto, Japan

Y. Mao
China Institute of Atomic Energy (CIAE), Beijing, P. R. China and
RIKEN, Institute for Physical and Chemical Research, Hirosawa, Wako, Japan

(Phenix-muon-96-13; submitted 9 November 1996)

1. Introduction

We have received 10 tubes from Pol.hi.tech, Italy in April, and 4 tubes from CIAE, China in July 1996. The test results on these tubes were shown at Santa Fe meeting. We had no problem to apply HV, 5.0 kV or more, for those tubes. But we have experienced difficulties applying HV for 20 tubes which were sent from CIAE in the middle August 1996. This is a brief report on our experience about these 20 tubes.

2. Iarocci tubes

The parameters of Iarocci tubes we have tested are given in Table 1.

Table 1: Parameters of Tested Iarocci Tubes
	Chinese (machine made)	Chinese (hand assembled)	Italian
length	5.6 m	5.0 m	5.1 m
cathode resistance	40 kohm	700 kohm	2 kohm
number of tubes	20	4	10

3. Twenty Chinese tubes

The 20 tubes were packed in one wooden box. No water drops was recognized when we opened the box. The tubes were wrapped with vinyl sheet, gas inlet and outlet were sealed with plastic ring and screw. We found that 1)One tube had a gas leak at the endcap and pin connection, and 2)One tube had a broken pin . We opened one tube for the inspection. The rest of the tubes (17) have been tested.

Each tube has a label which indicates Conditioning, Leakage check, Wire integrity, HV plateau, Working gas. HV curve up to 4.8 kV for each tube measured at China was attached to the box.

Just after arrival, we could only apply HV up to about 4.5 kV after a couple of days of trial. We started to try re-aging of these tubes from September. We have tried several ways of re-aging as summarized in Table 2. The gas used for the aging was Ar:isobutane = 25:75. The result of the re-aging for these 6 methods are summarized in Table 3. For tubes denoted "*", one step higher HV was tried but failed. For tubes "@", higher HV than listed was not tried. We could finally apply 5.0 or more to all the tubes in the end of October 1996.
Table 2: High Voltage Tolerance Tests. Test 6 denotes various tests which were done for individual tubes.
test 1 test 2 test 3 test 4 test 5 test 6

new or used new new 11 tubes used in test 1 or test 2, and 4 new tubes all used in test 3 all used in test 3 all used in test 3

blow out none 8 volume of Ar 10 volume of Ar 130 volume of N₂ 30 volume of Ar ***

test gas change before aging 4 volume 1.2 volume 1.2 volume 4 volume 4 volume ***

gas flow rate 48 cc/min 48 cc/min 48 cc/min 48 cc/min 480 cc/min ***

time needed for aging **no record** 4 days average 4 hours average 24-46 hours 2 hours average ***

number of tubes 6 7 15 4 6 3

Table 2: High Voltage Tolerance Tests. Test 6 denotes various tests which were done for individual tubes.
	test 1	test 2	test 3	test 4	test 5	test 6
new or used	new	new	11 tubes used in test 1 or test 2, and 4 new tubes	all used in test 3	all used in test 3	all used in test 3
blow out	none	8 volume of Ar	10 volume of Ar	130 volume of N₂	30 volume of Ar	***
test gas change before aging	4 volume	1.2 volume	1.2 volume	4 volume	4 volume	***
gas flow rate	48 cc/min	48 cc/min	48 cc/min	48 cc/min	480 cc/min	***
time needed for aging	no record	4 days average	4 hours average	24-46 hours	2 hours average	***
number of tubes	6	7	15	4	6	3

Table 3: Results of High Voltage Tolerance Tests. Each "*" denotes a tube for which one step higher in HV was tried but failed. Each "@" denotes a tube for which higher HV than listed was not tried.
HV (kV) test 1 test 2 test 3 test 4 test 5 test 6

3.8 *

3.9

4.0

4.1 *

4.2 *

4.3 * * *

4.4 **

4.5 **

4.6 ***

4.7 *

4.8 * **** *

4.9 ** *

5.0 * * @ @@ @@@@@ @

5.1 @@ @

5.2 @

5.3 @ @

Conclusions

For Chinese tubes, re-aging was necessary probably due to the contaminations (water?) during the transportation.
The cleaning process of the "blow out" with either dry N₂ or Ar gas is important before the re-aging. Without enough "blow out", we have experienced large leak current and after discharge.
The large gas flow rate was effective in the re-aging process. It prevents the continuous sparking which occur in the care of low flow rate. It's because the sparking discharge contaminates the gas and causes the difficulty to bring up HV.
After a tube becomes stable, the low flow rate is good enough.

Last Updated: 15 December 1996.

Webmaster, Los Alamos National Laboratory, Los Alamos, NM 87545 USA

HV (kV)	test 1	test 2	test 3	test 4	test 5	test 6
3.8		*
3.9
4.0
4.1		*
4.2	*
4.3	*	*	*
4.4		**
4.5	**
4.6			***
4.7		*
4.8	*		****	*
4.9			**	*
5.0	*	*	@	@@	@@@@@	@
5.1			@@		@
5.2						@
5.3			@			@