very forward instrumentation of the ilc detector
DESCRIPTION
Very Forward Instrumentation of the ILC Detector. Wolfgang Lohmann, DESY. Talks by M. Morse, W. Wierba, myself. BeamCal and LumiCal (Example LDC, 14 mrad):. LumiCal. TPC. HCAL. BeamCal. ECAL. precise (LumiCal) and fast (BeamCal) luminosity measurement - PowerPoint PPT PresentationTRANSCRIPT
September 2007 SLAC IR WS
Very Forward Instrumentation of the ILC Detector
Wolfgang Lohmann,DESY
Talks by M. Morse, W. Wierba, myself
September 2007 SLAC IR WS
BeamCal and LumiCal (Example LDC, 14 mrad):
LumiCal
TPC
ECA
L
HCAL
BeamCal
• precise (LumiCal) and fast (BeamCal) luminosity measurement
• hermeticity (electron detection at low polar angles)
• mask for the inner detectors
• GamCal ~150 m downstream for fast luminosity
September 2007 SLAC IR WS
Energy (GeV)
Eve
nts
Measurement of L
N
L = N /
Count Bhabha events
From theory
Goal: Precision <10-3
Eve
nts
, (rad)
Inner Radius of Cal.: < 10 μm
Distance between Cals.: < 600 μm
Radial beam position: < 1000 m
RL
6.10m
e+
e+
e- e-
IP
September 2007 SLAC IR WS
• Beam pipe (well measured in lab before installing, temperature and tension sensors for corrections) with installed BPM (BPM’s also on outgoing beam?)
• Laser beams inside ‘carbon’ pipe (need holes, but possible)
•Reflective laser distance measurement – accuracy ~1-5 µm, resolution ~0.1-0.5 µm•Mirrors glued to beam pipe•Calibration of sensors procedure – detector push-pull solution (?)
LumiCal mechnics and positioning
September 2007 SLAC IR WS
Simulations to optimise the Design
BeamstrahlungTeV per BX
electron from 2γ process
E.g. from UC Boulder
Head-on view
Side view
radial Axis
background
high energy electron
Efficient detection of high energy electrons is essential for search experiments
Finely segmented, compact calorimeter with fast readout
September 2007 SLAC IR WS
BeamCal & GamCal
Determination of beam parameters from beamstrahlung depositions on BeamCal:
2 mrad 20 mrad
Quantity Nominal Value Precision
x 553 nm 2.9
y 5.0 nm 0.2
z 300 m 8.5
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+09 1.E+10 1.E+11
N
Nu
mb
er/
BX
Pairs
BeamCal
Rough information on bunch crossing at low bunch charges
September 2007 SLAC IR WS
0
50
100
150
200
-200 -100 0 100 200
offset/2 (nm)
ener
gy
in g
amm
as (
MT
eV)
0
5
10
gammas
pairs
E BeamCal (TeV)
BeamCal & GamCal
Combine informations from pairs and photons (B. Morse)
Vertical beam offset
The ratio of the two quantities is proportional to the actual luminosity
September 2007 SLAC IR WS
Forward Region, example LDC
Vacuum Pump
BeamCal
LumiCal
QD0
Graphite Space for electronics/connectorscooling
Space for cables
Shielding Tube
BPM for FONTSi-pixel
September 2007 SLAC IR WS
The Mounting Procedure for BeamCal
1 montage of an auxiliary structure
2 montage of the first half barrel
3 Turn the barrel and bring the first calorimeter half barrel in final position
5 montage of the second half barrel
4 remove the auxiliary structure
To perform this procedure theupper half of the shieldingtube has to be removed
Installation and disassembly must bepossible without opening the vacuum!
September 2007 SLAC IR WS
•Forward calorimeters interfere with QD0, vacuum pumps, BPM’s, ballows, other beam diagnostics devices …….•We have to avoid matter in front of the calorimeters•LumiCal has challenging position accuracy requirements
Lets Stay in Touch
Summary
September 2007 SLAC IR WS
BeamCal
Efficient low angle electron vetoWhy:Background suppression in search channels, e.g.
Similar signatures,Two photon cross
section much larger
Background(two photon)
Signal expected from Susy
September 2007 SLAC IR WS
0
5
10
15
20
-200 -150 -100 -50 0 50 100 150 200
offset/2 (nm)
Lu
min
osi
ty (
10^
33 c
m^
-2/s
)
0
0.05
0.1
Lum
R
R (10-6)
Ratio of energy depositions in BeamCal and GamCal:
Almost proporti
onalto the
Luminosity!!!
GamCal &LumiCal
September 2007 SLAC IR WSCollabortion
High precision design
15
layers (z)
11 layers
(z)
4 layers
(z)
10 cylinders (θ)
60 cylinders (θ)
64 cylinders
120 sectors
30 rings
Parameter Pad Performance
Energy resolution 25%
resolution 3.5 * 10-5 rad
resolution 10-2 rad
~ 1.5 * 10-6 rad
Electronics channels
25,200
)( GeV
Pad
e-
Maximum peak shower
LumiCal, present understanding