RE: TOFr HV

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From: W.J. Llope (llope_at_physics.rice.edu)
Date: Mon Apr 07 2003 - 21:36:04 EDT

hi zhangbu - each caen HV "pod" has 4 output channels
so there's already two spare pos chs avcailable for use at
the present location...
some minor mechanical modifications to the "cage" are needed
but no big deal. regards

On Mon, 7 Apr 2003, Xu, Zhangbu wrote:

> 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
> > >
> >
> >
> 

-- 
_________________________________________________________
W.J. Llope, Ph.D.                  Res. Assoc. Professor
                 http://wjllope.rice.edu/default.html
                 llope_at_physics.rice.edu
T.W. Bonner Nuclear Lab.     
Rice University, MS-315      
6100 S. Main                       phone: 713-348-4741  
Houston, TX 77005-1892             fax:   713-348-5215
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