Report on tests ongoing in Perugia

Mauro Piccini, Roberto PiandaniINFN – Perugia and Perugia University

Outline

Test with PM in Neon

Measurement of time resolution of PM with the TELL1+Pisa TDC board set-up

( CEDAR samples form Phil)

Plane to glue the quartz windows in Perugia

PMs on Neon: first stepFirst attempt to separate PM (in Neon) from the divider (in air) using a feedthrough to be glued on the Aluminium (Steel) support.

Once HV test were performed in an air-tight boxfilled with Neon we saw discharges already at 600 V(working point at 900 V)

Question: discharges bewteen the PM pins and the external flange (connected to the ground) or between the pins themself?

The new feedthroughA new feedthrough was designed and produced to electrically separate the PM from the external flange

Results of the new testFake PM used for the test, in order to prevent any damage

Discharges have been seen between 600 and 650 V, slightly depending on the time taken to flux the Neon and on the output pressure of the Neon bottle (between 1.1 and 1.8 bar).

Once the discharge starts, to recover we have to strongly reduce the HV (below 100 V)

As a first step in the discharge, we see an increase of ~20% of the current going through the divider, then with few more tens of Volts the discharge is complete

Stopping to flux the Neon, the Neon itself start to be polluted by the air and the threshould for the discharge decreases down to 480 V

Confirmed the behaviour found by Piet in litterature

Remind on the divider

PM testMeanwhile, after the completation of the test of the first 500 RICH PMs (2010 sample), we test 50 CEDAR PMs supplied by Phil

Results in agreements with the tests performed on the RICH PMs

RICH PMs

Now our TELL1 is here at CERN to be replaced by a new one(hardware problem in the connections of a PP FPGA)Hoping to soon have the new one in lab to test the remaining 700 PMs of the 2010 sample

Planes to glue the quartz windowsWe obtain from INFN-Perugia the Clean Room (ISO 4, temperature and humidity controlled) as the place where to perform such operation

http://www.pg.infn.it/sez/laboratori/camera_pulita/clean-roomENG.htm

We are already in contact with a supplier company to buy the quartz windowsThe flange will be manufacted in Firenze

Ongoing work in Perugia:

Definition of a tool to uniformly distribute a fixed amount of glue in the surface where the window and the flange are in contact

Design of a system to measure the tightness of each window after the gluing

The choice between the vacuum vessel option and the “CO2” one, doesn’t affect the mechanical characteristic of this flange, in fact the same method exploited in 2007 and in 2009 can be re-applied