Below are plots of the
beam envelope in the HMS ( from exp. e01-002 )
for different z locations. Z = 0 is defined as midway between the HMS
drift chambers. The S1Y plane of scintillators is at z = 97.52 cm. +X
is up and +Y is beam left ( I have changed from the usual transport
coordinates) so it is like you are looking from the exit
of the dipole. The angles in the beam are small so the beam envelope
does not grow that much. Over 200cm distance in z the x width increases
by about 10cm and the y width by about 6cm. The main consideration for
the size is that for 20 degree scatter at the front face of the CH2
block one wants it to go through the same material no matter which x
and y position it had. Assuming the thickness of 60cm then this is an
additional +- 22cm in both directions. So I would suggest the CH2
be 144 tall and 104 cm and offset +5cm above the optics center.
1) Plot of X versus Y at z = 0. Plots with
no delta
cut. Plots
with abs(delta) < 10 . The red box is the HMS DC dimensions. The
blue lines in the 1d x plot are at -40 and +45cm. The blue lines in the
1d y plot are at -28 and 28.
2) Plot of X versus Y at z = 107.52. Plots
with no
delta cut. Plots
with abs(delta) < 10 . The blue lines in the 1d x plot are at
-45 and +55cm. The blue lines in the 1d y plot are at -30 and 30.
3) Plot of X versus Y at z = 117.52cm. Plots
with no
delta cut. Plots
with abs(delta) < 10 . The blue lines in the 1d x plot are at -45
and +55cm. The blue lines in the 1d y plot are at -30 and 30.
4) Plot of X versus Y at z = 204.92 cm. Plots
with no
delta cut. Plots
with abs(delta) < 10 . The blue lines in the 1d x plot are at -45
and +55cm. The blue lines in the 1d y plot are at -30 and 30.
5) Plot of X versus Y at z = 214.92 cm. Plots
with no delta cut. Plots
with abs(delta) < 10 . The blue lines in the 1d x plot are at
-45 and +55cm. The blue lines in the 1d y plot are at -30 and 30.