Re: Latest on radiation calc for Hall D (fwd)

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Tue, 11 Jun 2002 14:04:27 -0400
From: Pavel Degtiarenko <pavel@jlab.org>
To: Elliott Wolin <wolin@jlab.org>, Elton Smith <elton@jlab.org>
Cc: Bob May <may@jlab.org>
Subject: Re: Latest on radiation calc for Hall D

Elton, Elliott,

The link is the PDF file with the illustrations to the latest HallD model and
results:
http://www.jlab.org/accel/RadCon/RCGnotes/halldview.pdf

First 12 pages are different cuts of the model, along x, y, and z planes, with
details of the model geometry.
The model building has concrete walls of different thickness from 10 cm backward to
40 cm in the forward direction. The height of the walls is 5 m above the local grade
level. Above it, the "tin box" made of thin steel is assumed (0.6mm thick walls;
0.8mm thick roof). The target is 30 cm of liq.H2, positioned inside the iron
cylinder representing the coils, and the layers of lead representing the lead glass
calorimeter (barrel portion, and forward portion). The dumpline for the photon beam
is filled with He. The photon dump is 10 cm diameter and 1 m long hole in the dump
iron.

In the calculation, the photon beam starts in the beam line in the hall, assuming
the photon E/dE spectrum as it is shown in the first plot of the last page, and
power of 1.5 W.  The collimator enclosure, where 10 W of the beam is deposited, is
shielded enough not to contribute to the resulting dose rates.

The resulting dose rates outside the building are shown in the last page. Two plots
show the dose rates in the immediate vicinity of the North and South walls of the
Hall, next three plots show dose rates 9 meters from the North and South walls, and
15 m from the East wall, the last three plots show the dose rates 83 meters to the
North, South, and East walls (proposed site boundary).
This solution appears to be acceptable both from the point of view of site boundary
accumulated dose (less than 10 mrem per year = 2urem/hour * 5000 hours), and from
the point of view of the dose rates around the building (less than 100 mrem per year
= 50 urem/h * 2000 hours). The only additional safety measures would be the
requirement to restrict access to the truck ramp area (if the entrance door is
thin), and some restriction to perform elevation work close to the Hall (roof of the
counting house, light poles/fixtures, etc.)

If I missed something please contact me/ask questions.

Best regards,
Pavel