Revision as of 18:21, 20 April 2015

Started testing detector 4 again.

Fake stop time

Discriminator width was decreased from 40 ns (255 on discriminator display) to 6.3 ns (10 on discriminator display)

Discriminator threshold is set to 100 mv

The delay for the fake stop is set to 800 ns

CODA/CODAreader/ROOT_V5.30/R1DC/evio2nt -fr4516.dat > /dev/null

R1DC->Draw("(evt.TDC1190[1][6]-evt.TDC1190[2][6])/10>>(4096,-4096,4096)");

Run 4536

Below is a picture of the typical 800 ns fake stop pulse that should appear as a second hit in the Multihit TDC.

Now decrease delay of fake stop to 400 ns

PMT detector #4 HV at -1000 Volts

Run 4537 had a discriminator threshold set to 100 mv and the terminators were in. I see very few multiple hits in Detector 4

Now change threshold to 30 mv

Run 4538

I see two pulses from the discriminator but only one from the delayed fake stop (perhaps our delay module Ortec 416A is ignoring the second pulse)

Now change threshold to 16 mv

Run 4539

PMT detector #4 HV at -1000 Volts

Run 4540 had a discriminator threshold set to 16 mv and the terminators were out.

Run 4541 had a discriminator threshold set to 30 mv and the terminators were out.

Run 4542 had a discriminator threshold set to 100 mv and the terminators were out.

clearly one can turn up the threshold high enough to get rid of the ring with the terminators out.

But are the terminators reducing the ring effect by attenuating or by reducing reflections (the ring) in the output pulse.

@@ Line 83: / Line 83: @@
 [[File:r4542_PMT4_TDCmultihits.png | 200 px]]
+clearly one can turn up the threshold high enough to get rid of the ring with the terminators out.
+But are the terminators reducing the ring effect by attenuating or by reducing reflections (the ring) in the output pulse.