Any comments or suggestions on this proposal should be directed to
Elizabeth Gallas (eggs@fnal.gov) or Andy White (WHITE@UTAHEP.UTA.EDU).

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               PROPOSAL TO INCLUDE ICD PMT SHIELDING
               IN THE SOLENOID TEST PLANNED FOR 1998
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The ICD group has proposed to put an iron block just below each of the
4 pig troughs in Run 2 to shield the ICD PMTs from the magnetic field.
This iron will cause a local distortion of the field in this region.
Current calculations indicate that the force on the iron will be less
than 60% of the weight of the blocks in all field configurations
(solenoid and/or torroids on and/or off), and the corresponding
decentering force on the solenoid is non-trivial but within safety
limits.

We propose to include one or all of the 4 iron blocks in the detector 
for the D0 solenoid test currently scheduled for July or August 1998.

In addition, one of these blocks could be contained in a light-tight
crate which is partially instrumented to
1) measure the field at a few different locations in the crate,
2) measure light using some Hamamatsu PMTS from an LED based
calibration system.
Our reasons for participating in this test are many-fold:

1. We'd like to assure ourselves that the calculation of the field and
   forces  reflect  reality  for  the sake  of the  safe and  reliable
   operation of both the ICD and the solenoid.

2. Ransom has tested the tubes and  shielding in a variety of magnetic
   field environments  which we believe  reflect the range of possible
   field   configurations.  We have  found  that the  tubes  are quite
   susceptable  to  changes in the  direction  of the  field. While we
   believe we have  found a  shielding configuration  which will work,
   local field  distortions are difficult to  anticipate. We'd like to
   see  how well  the   phototubes work  in  the true   magnetic field
   environment.

3. Going through  the exercise of  mounting the iron  in a crate below
   the pig troughs will  be very helpful. In  the commissioning of the
   Run 2 detector, there  will be many other  complicating issues. For
   example,  a  light-tight  rectangular  box  containing  hundreds of
   delicate fibers  (fiber backplane) will be  mounted inside the back
   end of the  ICD crate  in Run 2.  We'd  rather not do  this for the
   first time during a tight  installation schedule a few weeks before
   we roll in.

4. The ICD group  is currently  entertaining 2  calibration options in
   Run 2. The first is  to learn to reuse the  Run 1 laser system in a
   useful way. The  second is to try an LED  based calibration system.
   We will  likely test  some  version of an  LED based  system in the
   solenoid test.