MICE PID size &scraping

MICE CM16, RAL, Oct 8 2006V. Palladino, Univ & INFN Napoli

for R. Sandrstromand others contributing to this effortYagmur, Holger, Alain and more

Definition of the problem

How wide has to be

the aperture of the downstream devices?

first of all, of the hole in the shielding slab, then, as a consequence, of the detectors

so to catch all muons relevant for MICE physics

that is, the ones that do not scrape anyway somewhere upstream

fully Active Scintillator

The new emerging layout

as compact as possible

activepreshower

Downnstream Up&Downnstream

Urgent!

Until hole in the shield is defined

size of detectors

magnetic field conditions at their PMTs

ie additional shielding provisions

remain undefined ….. “TRD chapter “ financial requirements precise plans for procurement

cannot progress as necessary

Analysis meeting on Sep 7 tackled finally the issue

Dear all,

as agreed yesterday at the analysis meeting I have put together a possible strategy for determining the size of the whole in the downstream detectors

We agreed that the quantity to define was the radius of the hole in the iron shield Preliminary ingredients are the knowledge of the end face of the cryostat and the material content and end-face of the tracker patch panel.

-1. determination of the low momentum limit of the calculation. We have to pick a number. If I take 200 MeV/c +- 15% as the nominal beam, two sigma down gives 140 MeV/c, and if I add to this the energy loss in three absorbers (33 MeV/c) I end up with 107 MeV/c. Let us take 100 MeV/c.

0. for the present set-up (R_shield = 250mm and z_shield could you please Rikard do the following:

take the existing 'full acceptance beam' and make the plot of momentum vs  maximum radius R_ts of the track in the region between z-in and z-out where z-in and z-out are the entrance and the exit planes of the iron shield. (~6.4 and 6.5 m at present)

Count how many muons of p= 100-200 MeV/c in the second tracker and within the tracker's fiducial cut at Rmax= 15cm are thus lost as a function of a possible cut in R_ts. Note as indication the radius for which we keep 99.9% of these muons. Is this less or larger than 25cm? (if it is less than 25 cm we know that we can have a smaller hole radius than what we now have)

meanwhile: 1. understand the closest distance that can be tolerated between the iron shield and the Sci-fi patch panel, including a reasonable safety margin. (I assume here that the closest is the best), zshield

2. once this is fixed generate field maps for a hole of  R_hole= 20, 25, 30 cm radius.

3. Repeat exercise 0 above for each radius of the hole. plot R_ts (99.9%) vs R_hole and calculate intersect where R_hole=R_ts (99.9%) this is the hole radius we want.

4. generate this configuration and calculate the resulting dimension of TOF2.

I hope this works

Alain

done, Yagmur

done, Holger

done, Yagmur

to be done, Rikard

so, not for this meeting …. but must be much before next !

Sep 8