Background in the muon spectrometer
This page gives the result of the different studies of
background in the muon spectrometer using the program GCALOR.
These studies have been used to optimize the shielding in ATLAS.
General studies
The gap. Starting with the Jul01 baseline
the gap between the ID and the LAr cal. was officially increased by 4 cm.
This shows the effect.
The beampipe
The flange. What is the effect of
adding a beampipe flange at z=13m i.e. after the JTT ?
The JM shield
The new JM plug. What is the effect of
attaching the JM plug to the LAr calorimeter ?
(Plot)
The JD shield
A smaller bore. What is the effect of
makeing the hole in the JD plug cylindrical with the same radius as the FCAL ?
The JT shield
A larger bore. What is the effect of
increasing the hole for the beampipe in the shielding ?
(Plot)
The JF shield
The steel JF. What is the effect of
changing the material in the forward shield JF from cast iron to steel ?
(Plot)
The JN shield
The steel monoblock. What is the effect of
changing the material in the monoblock part of the JN (which surrounds the TAS)
from cast iron to steel ?
Responsible for the content of this page is
V. Hedberg.
A summary of all studies and an introduction to the topic
is given in
Chapter 8 (Shielding Optimization) in
the ATLAS Radiation Background Taskforce Final Summary Document.
Detectors to measure the ATLAS radiation background. Presentation by Mike Schupe.
The results of the calculations below are mostly given as tables
in which the background for two different shielding
options are compared.
In order to understand the tables the following
information is available:
A table and
a plot of ATLAS indicating in which areas of the
muon spectrometer the background have been studied and a plot of the ID scoring regions.
A description of the different
particle rates that
are given in the tables.
A description of all
the shielding options that have
been tabulated.
A description of
the geometry and
the materials used in the
simulation is also available.
LIST OF TABLES
The paint. What is the effect of adding Boron to the
paint of the cavern walls ?
The toroid coils. What is the effect of
introducing the barrel toroid coils into the simulation ?
Comparison of the feb. 2002 baseline with all other options.
Comparison of the june 2002 baseline with all other options.
Comparison of two simulations of the same option i.e. an estimation of the stat. error
No second wall beampipe. What is the effect of
removing the second wall in the double walled beampipe sections after the LAr cal. ?
(Plot)
No beampipe. What is the effect of
removing parts of or the entire beampipe ?
(Plot)
Be beampipe. What is the effect of
changing 2 m of the beampipe into Be ?
(Plot)
Al beampipe. What is the effect of
changing the VA+VT+VJ beampipe into a 1.5 mm thick single walled Al beampipe ?
(Plot)
Boron in the JM disc. What is the effect of
doping the JM disc with Boron instead of Lithium ?(Plot)
The tungsten plug. What is the effect of changing
the material in the JD plug from Copper to Tungsten ?
(Plot)
Cylindrical hub in the JD. What is the effect of
changing the outer shape of the JD hub from a conical one to a cylindrical one ?
(Plot)
No conical pieces. What is the effect of
removing the conical pieces in the JD ?
Conical pieces made of Fe. What is the effect of
changing the material of the conical pieces in the JD from Cu to Fe ?
The 8cm cladding. What is the effect of
making all flat cladding on JD, JT and JF into 8 cm borated poly followed by 3 cm PB ?
(Plot)
The 5cm cladding. What is the effect of
making the cladding on the JD and the front cylindrical part of JF into 5 cm borated poly followed by 3 cm PB ?
The Pb loaded cladding. What is the effect of
making the cladding on the JD out of lead loaded polyboron ?
Poly-Cd in the cladding. What is the effect of
changing the cladding to 5% poly-Cd ?
Change dopant. What is the effect of
changing the concentration of the dopant in the polyethylene ?
Iron photon filter. What is the effect of
changing the lead photon filter to iron ?
The cladding in the JT. What is the effect of
different cladding scenarios in the toroid shield JT ?
(Plot)
The 8cm cladding. What is the effect of
making all flat cladding on JD, JT and JF into 8 cm borated poly followed by 3 cm PB ?
(Plot)
Cladding inside the toroid. What is the effect of
putting cladding inside the toroid ?
Poly-Cd in the cladding.What is the effect of
changing the cladding to 5% poly-Cd ?
Change dopant. What is the effect of
changing the concentration of the dopant in the polyethylene ?
Increase clearance.What is the effect of
increasing the clearance around the JTT poly from 1 to 4 cm ?
The new smaller JF design. What is the effect of
changing the shape of the outer conical pieces of the JF to cylindrical pieces ?
(Plot)
Reduction of the front part of the JF. What is the effect of
reducing the radius of the front part of the JF ?
(Summary)
(Plot 1)
(Plot 2)
No octogonal pieces. What is the effect of
removing or reducing the octogonal pieces in the JF ?
(Plot)
(Plot of rates versus Z and R)
No JF Shielding. What is the effect of
removing the entire JF shielding ?
The 8cm cladding. What is the effect of
making all flat cladding on JD, JT and JF into 8 cm borated poly followed by 3 cm PB ?
(Plot)
The 5cm cladding. What is the effect of
making the cladding on the JD and the front cylindrical part of JF into 5 cm borated poly followed by 3 cm PB ?
Poly-Li in the JF. What is the effect of
changing the cladding from polyboron + steel to only poly-Li ?
Poly-Cd in the cladding.What is the effect of
changing the cladding to 5% poly-Cd ?
An extra layer of poly-Li on the JF. What is the effect of
adding an 8cm thick layer of poly-Li to the JF ?
Change dopant. What is the effect of
changing the concentration of the dopant in the polyethylene ?
Iron photon filter. What is the effect of
changing the lead photon filter to iron ?
Reduction of the washers in the JN. What is the effect of
reducing the outer diameter of the washers in the JN or of changing the material
from cast iron to steel ?
(Plot)
No JN washers. What is the effect of
removing the JN washers ?(Plot)
Flux plots
Jan 2003 baseline:
Hadrons 20 MeV...
Neutrons...
Neutron 100keV...
Photons
June 2002 baseline:
Hadrons 20 MeV...
Neutrons...
Neutron 100keV...
Photons
December 2001 baseline:
Hadrons 20 MeV...
Neutrons...
Neutron 100keV...
Photons
The front octagonal is removed:
Hadrons 20 MeV...
Neutrons...
Neutron 100keV...
Photons
The radius of the back octagonal is reduced:
Hadrons 20 MeV...
Neutrons...
Neutron 100keV...
Photons
Front removed and the back octagonal is reduced:
Hadrons 20 MeV...
Neutrons...
Neutron 100keV...
Photons
Other information
JD-cladding simulation with FLUKA 2000 Study (by I. Dawson) of the effect of
removing the entire JD cladding or only the Pb layer on the JD.
Effect of beam-pipe on ATLAS cavern backgrounds Study (by I. Dawson using FLUKA) of the effect of
the beampipe on the background.
Last update:
13 January 2007
