Transcript Beam losses and radiation monitoring for steering the

BLMs - Radmon – BSCs – BCMs
for steering the beams in collision during the
engineering run at 450 GeV
Thijs Wijnands (TS/LEA), Richard Hall Wilton (TS/LEA),
Markus Stockner (AB/BI)
Input from : D. Kramer, C. Pignard, D. McFarlane, A. McPherson
Special Thanks :
A. Prokofiev, C. Ekström, TSL laboratories Sweden
W. Hajdas, R. Brun, PSI Villingen Switzerland
BLM ionization chambers
measure energy deposited by radiation in air
• On line measurements
– Dose rate
– Dose
• Resolution
– Spatial : 4000 devices around rings (also UX)
– Temporal : 90 ms – 100 s
– Signal : 2.5 pA – 1 mA
RadMon Radiation Monitors
energy deposited by radiation in Si
• On line measurements
– Dose rate, Dose
– Hadron flux (h > 20 MeV), fluence
– 1 MeV eq. neutron fluence
• Resolution
– Spatial : 307 devices, 250 in tunnel
– Temporal : 100 ms or more
– Signals :
• Dose, dose rate : 1 rad
• Hadron flux (h > 20 MeV) : 1e5 cm-2 s-1
• 1 MeV eq. n fluence : 1e10 n cm-2
Location BLMs and RadMons in tunnel
6 x BLMs at Q1 L8
RadMon under Q1 L8
BCM- Beam Condition Monitors
energy deposited by radiation in C (PCVD)
• On line measurements
– MIPS/s
– Dose (from degradation)
• Resolution
– Spatial : BCM1 (8 diamonds)
BCM2 (12 diamonds)
– Temporal : few ns – 40 ms
– Signal : 10 pA or more
A. McPherson, R. Hall-Wilton
BSC- Beam Scintillator Counters
energy deposited by radiation in plastic
• On line measurements
– MIPS/s
– Dose rate
• Resolution (CMS)
– Spatial : in front of HFC
– Temporal : 3-5 ns ?
– Signal : ?
Resolution Data to be confirmed …
Spatial resolution BCMs – CMS
At 10.9m :
• BSC1 - scintillators
At 25 m :
• RadMon, BLMs
IP
At 14.4m :
• BCM 2 - 12 diamonds
At 1.8 m :
• BCM 1- 4 diamonds
A. McPherson, R. Hall-Wilton
… another ~20 RadMon on cavern wall UXC55
Single bunch luminosities
Reasonable goal for first collisions would be ~ 4 x 1010 protons/bunch
From H. Burkhardt 26/01/07
Nominal dose rate & particle flux in TAS-Q1 region
IP1 and IP5, data from N. Mokhov LHC PR 633
ATLAS particle flux
M. Schupe
• For L = 2.5 x 1027 cm-2s-1 @ TAS
• dose rate
• hadron flux
: ~1 rad/s
: ~30 hadrons/cm/s
CMS particle flux
M. Huhtinen
• For L = 2.5 x 1027 cm-2s-1 @ TAS
• dose rate
• hadron flux
: ~3 rad/s
: ~10 hadrons/cm2/s
Measured response data
Proton data :
• BLMs
• RADMON
• BCM
• BSC
Neutron data :
• BLMs
• RADMON
• BCM ?
• BSC ?
1.8x104 gives 1 pA
1.0x105 gives 1count/s
2.2x107 gives 1 pA
1 count per proton ?
(60 MeV)
(60 MeV)
(24 GeV)
1.6x104 gives 10 pA
5x104 gives 1count/s
(174 MeV)
(174 MeV)
Preliminary data !
1 m long collimator
180 MeV p
Device
7Li(p,n)7Be
Relative Spectral Fluence [1/MeV]
BLM and RadMon calibration 180 MeV neutrons
10
10
10
neutron flux :
-1
Neutrons at 0 degrees
from 177.3 MeVprotons
on 24-mm 7Li target
Normalised : peak area = 1
-2
-3
0
20
40
60
80
100
120
Neutron energy [MeV]
140
8.8 x 104 s-1cm-2
A.V. Prokofiev, M.B. Chadwick, S.G. Mashnik, N. Olsson, and L.S. Waters.
Journal of Nuclear Science and Technology, Supplement 2, pp.112-115 (2002)
160
180
Neutron Beam facility at TSL
deflector magnet
Li target
stainless steel shielding
RadMon device under test
BLM- RadMon neutron irradiation
LHC BLM chamber
RADMON
SPS BLM chamber
D. Kramer, M. Stockner, C. Pignard, T. Wijnands
BLM- RadMon neutron response
Neutron Irradiation
40
Energy : 174.3 MeV
Flux : 1.7e5 n/cm2/s
Current [pA] or SEU [counts/s]
30
20
10
0
-10
SEU counts/s
BLM - LHC type
-20
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Time [s]
D. Kramer, M. Stockner, C. Pignard, T. Wijnands
Measuring luminosity at 450 GeV
L
N p, b *
BLM
RadMon
BCM
4 x 1010
11 m
-
-
-
-
-
-
1-10 pA
1 count /
10 s
?
cm-2 s-1
1.7 x 1027
1.3 x 1029 1.2 x 10 11
18 m
1.1 x 1030 1.2 x 10 11
2m
BRAN ?
450 GeV Commissioning with BSCs
• Start with 4x1010 – single bunch – 1 beam
–
–
–
–
–
background from beam gas
alignment errors
symmetry U-D and L-R
commission DAQ
repeat for beam pipe 2
• Background low :
– collide 2 single bunches
• Background high :
– increase bunch intensity
– collide 2 single bunches
– optimize lumi
• Increase nbr of bunches
– time resolution
From Zeus - DESY
Optimizing singe bunch luminosity at 450 Gev
• Expressing the separation of the two beams in sigma.:
– 1 sigma off in one plane, lumi drops by 22%
– 1 sigma off in both planes, lumi drops by 39%
– 2 sigma off in both planes, lumi drops by 87%
 At least L = 1.1 x 1030 cm-2 s-1 is needed
 2 sigma seems feasible, 1 sigma depends on S/N ratio
M. Lamont
Summary
• Radiation levels at L = 2.5 1027 cm-2s-1 will be extremely low :
– Only BSCs will provide some signal
– Commissioning Bran, BLMs, Radmons, BCMs, …
– Preliminary background in entire LSS1,5
• Increase first bunch intensity to, say, Np = 8 x 1010 to
–
–
–
–
Increase S/N ratio in BSCs
Enable first lumi scans
Confirm MC simulations, background
Check S/N ratio from Bran, BLMs, Radmons, BCMs, …
• If background sufficiently low : collisions with 2 or more bunches
• Open issues to be addressed :
– Resolution and response of BSC (CMS and ATLAS)
– BSC data exchange rate (5 Hz was proposed)
– Optimized layout BLMs, Radmons in LSS (from Q1 downstream)
Space in front of TAS at IP5 – BLM, Radmon
Q1
1 x Radmon
6 x BLMs + 6 x spare
Picture gallery
Example : Radiation Monitors in SPS 2006
10
hadrons [cm-2]
6
RADMON in TCC2 Test Facility
x 10
4
2
0
0
1
2
3
4
Time [days]
5
6
7
8
1
2
3
4
Time [days]
5
6
7
8
1
2
3
4
Time [days]
5
6
7
8
4
3
2
1
0
0
1 Mev eq. neutrons [cm-2]
Bending
Magnet M2
line wrong
Dose [Gy]
5
10
5
x 10
4
3
2
1
0
0
Example : Radiation Monitors in CDF (1)
antiprotons
N
W
E
S
RADMON radiation monitor
Example : Radiation Monitors in CDF (2)
Integrated values for High Luminosity runs Tevatron 2005
2
x 10
8
7
Outer (NW)
Outer (NW)
1.8
6
Inner (NW)
1.6
Inner (SW)
Inner (SW)
Outer (SW)
1.4
Outer (SW)
5
1.2
Dose [rad]
Hadron flux [cm-2]
Inner (NW)
1
0.8
0.6
4
3
2
0.4
1
0.2
0
0
10
20
30
40
50
60
Time [days]
70
80
90
100
0
0
10
20
30
40
50
60
Time [days]
70
80
90
100
Example : Radiation Monitors in CDF (3)
ES seperator accident FNAL 21 Nov 2005 :
– One of the electrostatic separators (ES) sparked
– Magnet Quench, Vacuum lost
– Several weeks downtime for repair
ONW INW
ISW
OSW Time
011
011
167
168
388
392
009
009
Nov 21 16:12:51 2005
Nov 21 16:13:06 2005
corresponding fluence : 4x106 cm-2 (h > 20 MeV)
Neutron response and resolution - BLM
300
BLM current [pA] or 10*Dump current [uA]
BLM current
250
Beam Dump current
200
150
For h > 20 MeV
100
50
0
0
0.5
1
Neutron Flux [cm2/s ]
1.5
2
5
x 10
LHC BLM chambers :
• linear response : 10 pA for 1.6 x 104 n/cm2/s
• noise level : 0.5 pA (analog measurement)
• resolution : 1 pA
D. Kramer, M. Stockner
Neutron response and Resolution - RadMon
45
180 MeV neutron Irradiation
Flux : 8.8 E4 n/cm2/s
40
35
Counts
30
25
20
15
10
5
0
0
200
400
600
800
1000
Time [s])
1200
1400
1600
1800
RadMon monitors :
• linear response : 2.6 counts/s @ 2.6 x 106 n/cm2/s
• spread : +/- 1 counts per 40 counts
• resolution 1 count
D. McFarlane, C. Pignard, K. Cwalina, T. Wijnands