RE: TOFr HV

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From: Xu, Zhangbu (xzb_at_bnl.gov)
Date: Mon Apr 07 2003 - 18:36:35 EDT

Hi,
  Sorry! I misunderstood what these all about.
  If it is just CAEN, do we have a spare?
Thanks!
      Zhangbu

-----Original Message-----
From: Geary Eppley
To: W.J. Llope
Cc: ''TOFp Operations ' '
Sent: 4/7/2003 6:28 PM
Subject: RE: TOFr HV

On Mon, 7 Apr 2003, W.J. Llope wrote:

>
> hi guys
>
> ...re: the humidity suspicions... it's a brand-new & modern
> power supply. somehow i just can't believe its so sensitive
> to humidity under normal operating conditions.... i agree at times
> trips have occurred somehow more frequently when the humidity
> is high, but i can't shake the gut feeling that this is simply an
> electronic problem and the humidity evidence is concidence... (?)
>
> when geary moves to ch-3 on the pos pod we'll have add'l info
> to help isolate what's really going on...
> BTW a possible sensitivity of the pigtail cabling to humidity is
> even harder for me to buy... we'll see...
>

Agree completely. Besides all the failure modes we have had in the last
3
weeks point 100% of the time to a failure in one channel of the CAEN and
0% of the time to any failure in a cable or in the detector.

Geary

> cheers
>
>
>
> On Mon, 7 Apr 2003, Xu, Zhangbu wrote:
>
> > Hi, Geary:
> > If it is humidity, do we need to open the pole tip to do something

> > on 16/04 (more isolation on the cables?)? I am not sure what to
> > do, just curious and hope the experts know.
> > Thanks!
> > Zhangbu
> >
> > -----Original Message-----
> > From: Geary Eppley
> > To: Xu, Zhangbu
> > Cc: 'TOFp Operations '
> > Sent: 4/7/2003 5:13 PM
> > Subject: RE: TOFr HV
> >
> > Hi Zhangbu,
> >
> > We know that the fist output channel of the positive CAEN supply is
> > bad. The second output channel is fine. The first output channel
seems
> > to
> > trip less with the lighter load of HVB, 9 modules, than with HVA, 19
> > module, load. There are some time periods of several days when the
> > first positive output doesn't trip and other periods when the first
> > output trips a lot. We have no real idea why some periods are worse
than
> > others but I was speculating on humidity.
> >
> > The fix on Wednesday will involve moving to the second and third
outputs
> > of the CAEN. We haven't tested the third output but have no reason
to
> > think it will be bad.
> >
> > Geary
> >
>
>

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