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Muon EDR material specification
O-ring choice:
In the inner part of the Muon system (M2/3 R1/2) we
have introduced an O-Ring to close and seal the
chambers.
Requirements to the O-ring are:
• Leak tightness
• High electrical resistance (in range of TΩ)
• Radiation hardness
• Chemical resistance to our environment
(combination of CF4/electrical field/radiation)
• Hardness of ~40 Shore A to optimize sealing and
number of screws used.
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Muon EDR material specification
O-ring choice:
A quite extensive research for commercial O-ring
material has been made to identify good candidates.
First an electrical test of all available material has
been done:
A quite large number of so called high technology
O-ring material did not fulfill the electrical
requirements. Due to the admixture of carbon (makes
the O-ring softer and black) the required high
electrical resistivity was often not reached.
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Muon EDR material specification
Table of tested O-ring material:
O-ring material
FPM EP
MVQ
A+P E60.1
HSS-Gelb NBR
SYNTHA NBR
A+P E 75.1
ALIMENTA
Soft compact
PARA SUPER
PARA SBR
CR BZS
CSM Elastomer
A+P S90.1
MVQ tube
NR 40
NR 45
NBR 50
CR 55
DIPLA NR/SBR
NR/SBR
Benola NBR/SBR
NBR/SBR Elastomerpl.
NBR Elastomerpl
Elastomerpl.
NBRMembrit
CR/SBR
CR/SBR standart
CR elastomer
NEOTEX CR/SBR
EPDM
EPDM
EPDM KTW
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colour
Hardness applied
Shore A voltage
rotbraun
yellow
w hite
beige
transp
brow n
red
black
gray
black
black
black
black
black
black
black
black
black
black
flexible
40
45
55
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
100
100
100
100
100
1000
1000
100
100
2000
100
100
74
1000
current
nA
2.1
0
5.6
0.6
6.5
2
3.5
0
0
0
1.9
1.2
8
0
0
0
9.7
0
9600
68000
35000
500
18000
2000
45
12000
200000
130
62000
7000
370000
9800
R
TΩ/cm
available
Ø 3mm
remarks
0.42
out of sensitivity
0.17
1.52
0.35
0.45
0.26
out of sensitivity
out of sensitivity
out of sensitivity
no
0.48
0.65
0.11
out of sensitivity
out of sensitivity
out of sensitivity
0.103
out of sensitivity
T.Schneider/LHCb Muon EDR
yes
yes
yes
candidate
candidate
candidate
yes
candidate
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
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Muon EDR material specification
O-ring choice:
The choice of “soft” (40 shore A) commercial material
corresponding to our requirements is limited somehow to natural
rubber (NR) and silicone material (MVQ).
Silicone would have the advantage that one can get it as soft as
needed but the risk of out-gazing Silicone particles made us
choosing natural rubber. Therefore natural rubber has been used
for all our proto-types.
Preliminary aging tests in Gif have given good results (full
chamber)
A total dose radiation test in Sanita will be performed soon
(only O-ring)
An additional aging test in Casaccia is foreseen in June/July 2003
(full chamber)
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Muon EDR material specification
Wire specification for gold plated tungsten wire:
• 30μm gold plated tungston wire with a max tolerance
of ±2% in diameter
• Weight per meter wire: 13.55mg
• Gold coating thickness: 0.3μm
• Grade of straightness 1:
Free hanging distance /wire length=95/100
• Spools of Ø95mm
• For the preproduction wire has been ordered from
LUMA
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Muon EDR material specification
Preliminary test on HV resistors:
• On 2 sets of 0.25W resistors a spark test has been
performed
Type
MMA
0.25W
100KΩ
#
10
11
U(KV)
2.7
3.2
2.9
#Sparks
260000
65000
28000
Results
no change
4 resistors changed to MΩ values
no change
• A substantial change of resistor value appears only after
many thousands of spark (wire can keep ~1000 sparks?)
• No resistors were mechanically destroyed
• For our application (2mm pitch; 2.7KV) we will use
0.4W resistors. (same dimensions as 0.25W)
• More extensive test will be done as soon we have the
0.4W resistors in hands
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