Transcript Xenon Detector Status - Paul Scherrer Institut

Xenon Detector Status
Liquid Xenon Group
Outline
• Cryostat construction
– Honeycomb panel test at Pisa
– Assembly
– Cryogenic test at SIMIC
– Leak test at PSI
• Detector preparation at PSI
– Alignment at PiE5
– PMT installation
• Schedule
1
Cryostat delivery to PSI
• Delivery to PSI on 5/June
• 6 weeks delay from the
schedule reported in the
previous review meeting
– Delay of construction
• not due to a technical problem
– Delay of the cryogenic test at
SIMIC
• Difficulty to stop leak
2
Honeycomb panel test completed
• 3rd panel delivered to Pisa at 16:30
on 20/Feb
• Mounted on the text box and tested
on 22, 23/Feb
– 3 bar
– Inspection by a Plyform expert
– 4 bar x4 times
• Hold for 3 minutes at 4 bar in the last
test
– Panel deformation (max)
• 0.3 mm at 1 bar
• 3.4 mm at 4 bar
Holes for
evacuation
3
Inspection of the panel
4
Low temperature test
• Wrapped with
insulators and
cooled with LN2
• Pressurized with
compressed air
– 2 bar
– No damage on
the panel found
5
And mounted on the cryostat
• 400 micron carbon-fiber plate
between the panel and window
to fill the gap
As of 13/Mar
6
Cold and Warm Vessel Assembly
As of 19/April
7
Cryogenic Test at SIMIC
•
-18/May
–
•
21/May
–
•
He leak test. 1.8Bar He was filled and found that
the leak rate was larger than 10-4 mbarl/sec.
Keep evacuation during the night.
22/May
–
•
All nuts on the covers of the cold vessel were
fastened tightly and the warm vessel was
evacuated whole weekend.
cooling using cold gas from the LN2 tank. Cold
gas in the cold vessel Most parts were cooled
down to -5~-10 degree C.
23/May
–
–
liquid N2 through the cooling pipe. All parts
cooled below -110 degreeC around 12:00.
Then N2 gas at 1.0Bar and He gas filled step by
step with measuring leak rate.
•
•
•
•
•
•
N2 1.0 bar He 0.2 bar  5x10-7 mbarl/sec
N2 1.0 bar He 0.4 bar  1.6x10-6mbarl/sec
N2 1.0 bar He 0.6 bar  7.8x10-6mbarl/sec
N2 1.0 bar He 0.8 bar  2.2x10-5mbarl/sec
The leak was not fixed at SIMIC by any
means.
We decided to bring the cryostat to PSI and
perform a leak test
8
Cryostat arrived at PSI
• Delivery at 7:00 am on 5/June
• Works to be done
Cleaning
Leak/pressure test
Alignment
– PMT installation
–…
9
Leak and Pressure Test at PSI
• The metal gasket was not compressed
correctly due to deformed shape of the
flange
• Re-machining the flanges by hand
• Supporting structure installed to
evacuate the inner vessel for the leak
test
cover
flange
gasket
10
Leak Test at PSI
• Finally we found a hole on the welding line of the thin
window!
11
Leak test again
• After closing the hole, we performed a leak test again (with recycling
the metal gaskets and with viton O-rings)
• Cracks found at corners
– Eddy-current measurement
• US-bottom d1.3mm L7mm, -top OK
• DS-bottom d0.8mm L13mm, -top d0.8mm L5mm
• It was confirmed that these did not cause leak.
• In the end we confirmed the tightness of the cryostat by using viton
O-rings.
– Leak rate < 3x10-9 mbarl/sec
12
Alignment at PiE5
• Decide the cryostat position on the platform.
• Check how we can install the cryostat in the electronics hut
13
Alignment at PiE5
• Alignment of the cryostat
– PMT support is aligned relative to the beam line within
an accuracy of 1mm
– Cryostat leg positions determined on the platform
• Screw holes to fix the legs
• G10 insulator between the platform and legs
14
Piping and cabling
• Working in a clean hut
• Cabling from patchpanels to feedthru almost finished
• LN2, GXe, LXe piping is ongoing in parallel to PMT
installation
15
PMT installation
• Patchpanel – Feedthru cabring
completed
• PMT installation started on 8/July
– Outer and Top PMT installation
completed on 9/July
– Now working on the inner (as of
12/July)
16
Schedule
•
•
•
•
•
PMT installation, -19/July
PMT test at room temperature, 20-23/July
He leak test, 25-28/July
Ready to move to PiE5 on 30/July
Evacuation and liquefaction in August
– 950 liter xenon is already liquefied
• Alpha/cosmic runs at the end of August
– In parallel to purification
– Monitor xenon purity
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