Meeting with Radcon

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Mon, 17 Apr 2000 17:08:27 -0400 (EDT)
From: Elton Smith <elton@jlab.org>
To: may@jlab.org, pavel@jlab.org, schwahn@jlab.org
Cc: elton@jlab.org, Elliott Wolin <wolin@jlab.org>
Subject: Meeting Mon 17 


I made the following notes from our meeting. Please comment or send
corrections:

1. Drawings required (plant engineering)

a) Plan view
b) Collimator Region
c) Transverse cuts
   - radiator
   - exit of tagger building
   - e- beam dump
   - photon collimator
   - hall D target

2. Hall D sky neutron shielding (no action necessary at this point)
   - For now use conservative estimate of 10-cm thick concrete

3. Fix distance of radiator to e-dump (Radcon and Hall D)
   Inputs to do this:
   - Use vertical bend(*) (in addition to horizontal bend)
   - center of dump must be at ground level or below
   - Review this idea with Hall Crannell
   - Input from site-boundary dose considerations

(*) Note: Current magnet is sized to bend the beam by 9deg horizontal.
Therefore the composite vertical + horizontal bend is limited to this
angle.


4. Muon Shielding (RadCon)

a) First Priority: Shielding of muons from electron beam dump
   - undertanstand muon production angular distribution, and how this
     might affect Hall D detector
   - longitudinal and lateral fluxes

b) Second Priority: Shielding of muons in photon line
   - Determine width of Fe shielding
   - Flux from both collimator region and hall D target (*)

(*) Note: Photon power on Hall D target is 1.5 W (max). However the
typical target is 30 cm of hydrogen (3.5% of a radiation length), so
typical power deposition in the target is only 53 mW.

5. Ground Water from Electron Dump: Add following statment to Design
   Report: 

The Jlab RadCon group has a successful record of complying with state
regulations related to ground water activation for Halls A and C, which
are rated up to one MW. The existing process for monitoring and
verification of ground water contamination from these beam dumps will be
modified appropriately for various factors including hydrogeology, to
handle any contamination from the 60 W electron beam dump for Hall D.



 Elton Smith
Jefferson Lab
elton@jlab.org
(757) 269-7625