Cobra shielding

[Francoise Mulhauser <Francoise.Mulhauser@psi.ch>]

Hi,

Yesterday, during the bi-weekly "montage" meeting, we have
spoken about the MEG shielding implementation. you have to
know the following information:

1. The MEG and magnet group have calculated the effect of
   floor and wall shielding for the piE3 are. It should
   reduced the average field from 4-5G to 1-2Gauss.
2. The MEG people are NOT allowed to use the Cobra magnet
   during the time L.Simmons is measuring in the piE5 area,
   namely the entire September-October months.
3. The MEG people will use intensively the Cobra magnet
   starting in November. They have also implemented a MSCB
   signal which available on the net, for user to have the
   magnet on/off and intensity.
4. The installation of the shielding will thus take place
   during the exchange between MuLan and MuCap. The
   hallendienst is responsible for it.

Now the problems:

1. The muSR people (ALC) believe that they can NOT measure with
   the shieling in place, because of the effect of the PSC
   magnet on it.
2. Robert is of the opinion that the PSC magnet will create
   a remanance magnetic field in the shield which is much
   bigger than the field we want to be protected from.
3. Therefore, we have installed on the bottom of the PSC
   support, one of the forseen iron plate. We are now
   measuring the actual field of the plate (between 2-30G at
   B=0T for PSC, because the plate where previously used in
   the piotron). The "air" field is around 1G around the
   plate.
4. At B=5T, we are measuring value up to 500G on the
   plate. Now we are going down with it and will measure the
   remaining field.

This to say that we may have to install the shield only for
MuCap and MuLan and to remove it for ALC. The hallendiesnt
will cut the different pieces for the floor, with the holes
for the rails. The space up to the last triplet (included)
will be covered by the 10mm thick iron.  The wall piece
may/will be done in one piece that they can transport
easily. To do so, the power distributors and ALC cable box
will be shifted to the back wall of the area, where they
should not bother us at all.

More news may come later on.

Best regards

Francoise