Yiftah Silver, Dan Levin 1

UM lab activity

Status report Dec. 7

December 7, 2010

Hardware progress

• We have managed to connect both DRS4 boards to the panel.

• 4 RO channels and 4 HV channels at the same time.

• A 4X4 array of pixels is available for measurements – a 2D detector.

• Same connectors as last week.

Yiftah Silver, Dan Levin 3

Rout=100[Ohm]

11/30/2010

HV

Rq=22MOhm

SnO2

Attenuators: For HV line:20dB &inverter

For RO line 20dB+20dB

Ni

Set-UpCHV=2pf

2 DRS4 boardsDiscrimination threshold:

For RO lines: -0.5VDRS4 trigger

Common trigger – OR on all RO channels

Bkg measurements

• A measurement of hit rate over time was made on one pixel (12X30) with the LabView program and the scope.

• The measurement is of RO line 12 after a (10X attenuator).

• 24 consecutive hit rate measurements were made, each 15 min long – total of 6 hours.

Hit rate over time (12X30)

From the same measurement:Rise time distribution is obtained by subtracting the time of the point 10% of the peak from 90% of the peak, without any fits.

Few hits were at -20V

Measurements on 4X4 array

• A set of measurements were made with the DRS4 boards.

• 3 min measurement of bkg • Followed by a measurement when the

collimated Sr90 is above the 4 center pixels.• Pulse height distributions were made for each

pixel separately at each of the conditions.• “Lego” plots were made for visualization.

Measurements on 4X4 arrayPV1 99%Ar- 1%CF4 700 Torr , 850V

Subtraction of the bkg from the source

The source is clearly seen in the center of the array of pixels

Pulse height distribution 4x4 bkg

X axis – mV (this is after 2 attenuators X10 each)

Shown here are pixels (10,11)X(29,30)

Pulse height distribution 4x4 bkg

X axis – mV (this is after 2 attenuators X10 each)

Shown here are pixels (12,13)X(29,30)

Pulse height distribution 4x4 bkg

X axis – mV (this is after 2 attenuators X10 each)

Shown here are pixels (10,11)X(31,32)

Pulse height distribution 4x4 bkg

X axis – mV (this is after 2 attenuators X10 each)

Shown here are pixels (12,13)X(31,32)

Pulse height distribution 4 center pixel under source

X axis – mV (this is after 2 attenuators X10 each)

Shown here are pixels (12,13)X(31,32)

Bkg hit measurement on 4X4 array

• We used the common trigger for counting the rate on the 16 pixels.

• 60 consecutive measurements were made, each of 15 min (as before) total of 15hours.

• Measurement started at Sat. Dec.3 at 6PM• Connected pixels: RO lines: 10-13

HV lines: 29-32• As before: 850V

Rate over time (16 pixels)

A few hours later, no pulses were seen at 850V at all.When voltage was raized to ~870 a fast rate was observed but coming only from one pixel (10X32)The signal itself was different – lower &slower.

The beginning of the measurement shows the same behavior as the measurement of one pixel, But, Clearly something happened after ~7 hours

A few hours later and @870 V

Summery

• Background needs to be further investigated, after a suck n’ bake we shall replace the current Gas with a new one (still Ar-CF4 at the same pressure and percents) and will try to repeat the hit rate over time experiment.

• it seems that both the pulse height and rise time distributions are very narrow but a better examination is needed because of unexpected peaks.