Xenon Detector Status Liquid Xenon Group Outline Cryostat

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 Pi. E 5 – 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 • 3 rd 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 x 4 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 LN 2 • 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 – All nuts on the covers of the cold vessel were fastened tightly and the warm vessel was evacuated whole weekend. • 21/May – He leak test. 1. 8 Bar He was filled and found that the leak rate was larger than 10 -4 mbarl/sec. Keep evacuation during the night. • 22/May – cooling using cold gas from the LN 2 tank. Cold gas in the cold vessel Most parts were cooled down to -5~-10 degree C. • 23/May – liquid N 2 through the cooling pipe. All parts cooled below -110 degree. C around 12: 00. – Then N 2 gas at 1. 0 Bar and He gas filled step by step with measuring leak rate. • • • N 2 1. 0 bar He 0. 2 bar 5 x 10 -7 mbarl/sec N 2 1. 0 bar He 0. 4 bar 1. 6 x 10 -6 mbarl/sec N 2 1. 0 bar He 0. 6 bar 7. 8 x 10 -6 mbarl/sec N 2 1. 0 bar He 0. 8 bar 2. 2 x 10 -5 mbarl/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 üCleaning üLeak/pressure test üAlignment – 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 d 1. 3 mm L 7 mm, -top OK • DS-bottom d 0. 8 mm L 13 mm, -top d 0. 8 mm L 5 mm • 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 < 3 x 10 -9 mbarl/sec 12

Alignment at Pi. E 5 • Decide the cryostat position on the platform. • Check how we can install the cryostat in the electronics hut 13

Alignment at Pi. E 5 • Alignment of the cryostat – PMT support is aligned relative to the beam line within an accuracy of 1 mm – Cryostat leg positions determined on the platform • Screw holes to fix the legs • G 10 insulator between the platform and legs 14

Piping and cabling • Working in a clean hut • Cabling from patchpanels to feedthru almost finished • LN 2, 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 Pi. E 5 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 17

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