CDC 06 02 2008

1 News on the noise issue

Inspired by Gerard's visit and equipped with his differential probe I had a first look at a non-oscillating preAmp. I put 1900 V on the straws and checked all connected straws and they are all looking good (= I see signals). Time to do some additional noise studies.

Setup:

*) 16 armed straws
*) HVDB that Gerard brought with him
*) new preAmp, also the one the Gerard brought with him
*) 1.5 meter cable + differential probe (which attenuates the signal 0.366x) (NO shaper) + scope

The VME crate was switched off, the only thing on (within a radius of 10 m) was a PC and a NIM crate.

I took a first look at the noise on a random straw (shown in figure 1.1):

figure 1.1: The noise on a random straw (average).

Pickup with a frequency of 67.80 kHz can be observed. It was coming from a CRT computer screen, so that was switched off.

For further studies i selected 4 typical channels/straws: i will call them straw 1,2,3, and 4. The scope traces of these channels ()respectively are shown in figure 1.2-1.5:

figure 1.1: The noise on straw 1(average).

figure 1.1: The noise on straw 2(average).

figure 1.1: The noise on straw 3(average).

figure 1.1: The noise on straw 4(average).