Plots from CPR tube tests : B field tests
KA2626 : -550 V
N.D. 1.0 : roughly 1000 photoelectrons
Definition of the
coordinate system.
Same as
Hamamatsu
in y and z, the opposite direction in x.
Note the respose plots below comes with the back view
(cross talks are the front view, ok).
Will fix this later.
B field along x or y axis.
Created by a pair of magnets.
Field is 30- 40 Gauss, fairly uniform,
and almost zero ( < 0.5 G )
for other components.
B field along z axis.
Created by magnet at the bottom of the tube case.
Field at the outside of the cathode surface
of the tube is about 2 Gauss (center)
and 5 Gauss (outer channels).
Must be stronger insdie closer to the bottom,
namely at the dynodes and anodes.
Also x and y components may be non-negligible (up to 2-3 Gauss)
Conclusions:
Compatible with Hamamatsu results (which is for 64-channel version, though).
Most affected by B field in negative y direction.
Not really sensitive to B field in x (+ or -) direction.
Can be
sensitive in -z direction.
Cross talk changes are totally unnoticeable
even at 50 Gauss in x or y, and a few G in z.
Overall, 1-Gauss fields expected inside the mu-metal shields
should not affect anything at all.
Fumihiko Ukegawa
Last modified: Mon Jan 20 17:48:41 JST 2003