1. 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

2. 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

3. 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

4. Location BLMs and RadMons in tunnel
RadMon under Q1 L8
6 x BLMs at Q1 L8

5. 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

6. 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 …

7. Spatial resolution BCMs – CMS
At 10.9m :
BSC1 - scintillators
At 25 m :
RadMon, BLMs IP
At 1.8 m :
BCM 1- 4 diamonds
At 14.4m :
BCM diamonds
A. McPherson, R. Hall-Wilton
… another ~20 RadMon on cavern wall UXC55

8. Single bunch luminosities
Reasonable goal for first collisions would be ~ 4 x 1010 protons/bunch
From H. Burkhardt 26/01/07

9. Nominal dose rate & particle flux in TAS-Q1 region
IP1 and IP5, data from N. Mokhov LHC PR 633

10. ATLAS particle flux For L = 2.5 x 1027 cm-2s-1 @ TAS
M. Schupe
For L = 2.5 x 1027 TAS
dose rate : ~1 rad/s
hadron flux : ~30 hadrons/cm/s

11. CMS particle flux For L = 2.5 x 1027 cm-2s-1 @ TAS
M. Huhtinen
For L = 2.5 x 1027 TAS
dose rate : ~3 rad/s
hadron flux : ~10 hadrons/cm2/s

12. Measured response data
Proton data :
BLMs 1.8x104 gives 1 pA (60 MeV)
RADMON 1.0x105 gives 1count/s (60 MeV)
BCM 2.2x107 gives 1 pA (24 GeV)
BSC 1 count per proton ?
Neutron data :
BLMs 1.6x104 gives 10 pA (174 MeV)
RADMON 5x104 gives 1count/s (174 MeV)
BCM ?
BSC ?
Preliminary data !

13. BLM and RadMon calibration 180 MeV neutrons
1 m long collimator
180 MeV p
Device
7Li(p,n)7Be
neutron flux :
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 (2002)

14. Neutron Beam facility at TSL
deflector magnet
Li target
stainless steel shielding
RadMon device under test

15. BLM- RadMon neutron irradiation
LHC BLM chamber
RADMON
SPS BLM chamber
D. Kramer, M. Stockner, C. Pignard, T. Wijnands

16. BLM- RadMon neutron response
D. Kramer, M. Stockner, C. Pignard, T. Wijnands

17. Measuring luminosity at 450 GeV
cm-2 s-1
Np, b*
BLM
RadMon
BCM
1.7 x 1027
4 x 1010
11 m -
1.3 x 1029
1.2 x 10 11
18 m
1.1 x 1030
2 m
1-10 pA
1 count /
10 s ?
BRAN ?

18. 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
optimize lumi
Increase nbr of bunches
time resolution
From Zeus - DESY

19. 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

20. Summary
Radiation levels at L = 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)

22. Space in front of TAS at IP5 – BLM, RadmonQ1
1 x Radmon
6 x BLMs + 6 x spare

23. Picture gallery

24. Example : Radiation Monitors in SPS 2006
Bending Magnet M2 line wrong

25. Example : Radiation Monitors in CDF (1)
antiprotons N S E W
RADMON radiation monitor

26. Example : Radiation Monitors in CDF (2)
Integrated values for High Luminosity runs Tevatron 2005

27. 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
Nov 21 16:12:
Nov 21 16:13:
corresponding fluence : 4x106 cm-2 (h > 20 MeV)

28. Neutron response and resolution - BLM
For h > 20 MeV
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

29. Neutron response and Resolution - RadMon
RadMon monitors :
linear response : x 106 n/cm2/s
spread : +/- 1 counts per 40 counts
resolution 1 count
D. McFarlane, C. Pignard, K. Cwalina, T. Wijnands