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Physics at LHC Prague, 6-12 July 2003. Elastic scattering at TOTEM: optics & detectors. V. Avati University of Helsinki on behalf of the TOTEM Collaboration http://www.cern.ch/Totem/. Collaboration. Historical : CERN Tradition (PS-ISR-SPS) - PowerPoint PPT Presentation
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Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
V. Avati
University of Helsinki
on behalf of the
TOTEM Collaborationhttp://www.cern.ch/Totem/
Elastic scattering at TOTEM: Elastic scattering at TOTEM: optics & detectorsoptics & detectors
Physics at LHCPhysics at LHC
Prague, 6-12 July 2003Prague, 6-12 July 2003
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Università di Bari and Sezione INFN, Bari, Italy
Institut für Luft- und Kältetechnik, Dresden, Germany
CERN, Geneva, Switzerland
Università di Genova and Sezione INFN, Genova, Italy
Institut des Sciences Nucléaires, IN2P3,/CNRS, Grenoble, France
University of Helsinki and HIP, Helsinki, Finland
Warsaw University of Technology,Plock, Poland
Academy of Sciences, Praha, Republic Czech
Brunel University, Uxbridge, UK
Collaboration
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
The measurement ofThe measurement of tottot
• Historical : CERN Tradition (PS-ISR-SPS)
• Dispersion relation fit (logs) , =2.20.3
• Current models predictions: 100-130mb
• Aim of TOTEM: ~1% accuracy
• Absolute calibration of Luminosity
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
02
2
1
16L
t
tot dt
dN
inelasticelastictot NN L inelel
ttot NN
dtdN
0
2
)/(
1
16
(Optical Theorem)
~150m
~220m
-6.5<<6.5
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
LOW t measurement angles ~ 10-2 mrad
At the IP : small beam divergence [ large * large beam size [x
At the detector stations:
y = Ly y*+ vy y* L = ()1/2 sin (s)
x = Lx x *+vx x*+Dx v= ()1/2 cos (s)
Optimal conditions:
• parallel to point focussing planes (v=0) unique position-angle relation• largest Leff sizeable distance to the beam center (~1mm)• lowest emittance (10-6 m. rad )
Luminosity : 1028 cm-2 sec-1,36 bunches (with *=1100 m) An alternative optics (*=1540m) is under study: interesting feature and better performances
- parallel to point focussing planes in x and y simultaneously at ~220 m - better “one arm resolution”
Special optics for the measurement of the forward proton(s)
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
vx(1100)
vy(1100)
vy(1540)
vx(1540)
Ly(1100) Lx(1100)
Lx(1540)
Ly(1540)
v= ()1/2 cos (s)
L = ()1/2 sin (s)
High optics: lattice functions
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
* = 1100 m
Elastic Scattering
* = 1540 m
acceptance
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
t-acceptance (50%) vs detector position
(%)
Number of events
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Errors on the extrapolation to t=0
1. Beam angular divergence
2. Optical functions
3. Beam position
4. Crossing angle
5. Detector resolution: statistical and systematical (detector offset)
6. RP station alignement
7. Background (beam halo, double pomeron exchange…)
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
t-resolution (one and two arms) versus detector resolution
beam angular divergence =0
total (t)/t (1 arm)
v dependence!
(t)/t (2 arms)
coplanarity
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Coplanarity test, background rejection: resolution
Detector resolution = 20 m
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
=1100mt=0.004 GeV2 A=44%t=0.01 GeV2 A=67%
=1540m t=0.004 GeV2 A=64.4%t=0.01 GeV2 A=78.2%
Acceptance dependence from detector offset
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Elastic Cross section (t=0): stat. and syst. errors
L=1028 cm-2 s-1
run time = 4 . 104 sec
10m detector positionuncertainty
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
1 eff.day (105sec) at high and 18 m
d/
dt
(pp
) (m
b/G
eV
2)
(M. Islam)
Large t scattering
-t(GeV2)
15/GeV2
27.103/GeV2
Ldt = 1033 1037 cm-2
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Acceptance
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
~3cm
CMS Hybrid
Detector requirementsDetector requirements High and stable efficiency near the edge High and stable efficiency near the edge
facing the beam, edge sharpness < 10 facing the beam, edge sharpness < 10 mm Try to do better than present technology guard
rings ~0.5 mm
Detector size is ~ 3 x 4 cmDetector size is ~ 3 x 4 cm22
Spatial resolution ~ 20 Spatial resolution ~ 20 mm Moderate radiation tolerance Moderate radiation tolerance
(~10(~101414 n /cm n /cm22 equiv) equiv)
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Cold SiliconCold Silicon RD39/NA60 have investigated/used silicon at cryogenic
temperatures (~ 100-130 K) Studies hint at possibility of operating silicon microstrip without
guard rings at LN temp.K.Borer et al., “Charge collection efficiency of irradiated silicon detector operated at cryogenic temperatures” NIM A
440 (2000) 5. L.Casagrande et al.,"A new ultra radiation hard cryogenic silicon tracker for heavy ions beams“ NIM A (2002) 325-329.S.Grohman et al., “Detector development for TOTEM Roman Pots”, IX Blois Workshop on El. and Diff. Scatt., Pruhonice,
Czech Republic, (2001), 363.
In 2002 we have performed a first measurement on cold edgeless In 2002 we have performed a first measurement on cold edgeless silicon detectorsilicon detector
Z. Li et al, "Electrical and TCT characterization of edgeless Si detector diced with different methods", IEEE NSS Proc., San Diego, Nov. 2001
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
Hits in the telescope(all good tracks)
Hits in the cut detector
Reconstruction of the cut Reconstruction of the cut edgeedge
Effi
cie
ncy
Effi
cie
ncy
Edge at: 0+20micron
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHCDevelopment with planar Development with planar
technologytechnology
n+ ring (20 n+ ring (20 m) atm) at mm from p+from p+
set at the same pot as backplaneset at the same pot as backplane
hope:hope:
n+ ring stops the n+ ring stops the C C currentcurrent
B under control with temperatureB under control with temperature
test of various configuration this test of various configuration this summersummer
goal:increase of operation goal:increase of operation temperaturetemperature
cut edge
p+
n+ AB
D
p+
n+
AB
C
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
PLANAR-3D DETECTORS TRADITIONAL PLANAR DETECTOR + DEEP ETCHED EDGE FILLED WITH POLYSILICON
E-fieldp + Al
n + Al
Edge sensitivity ~20 m Leakage current =6nA at 200VBrunel, Hawaii, Stanford
n + Al
i
0
2
4
6
8
10
12
14
16
0 100 200 300 400 500 600 700 800 900 1000
Signal
Sca
n P
osi
tion
(mic
ron
s)
PreliminaryPreliminary
0
2
4
6
8
10
12
14
16
0 100 200 300 400 500 600 700 800 900 1000
Signal
Sca
n P
osi
tion
(mic
ron
s)
PreliminaryPreliminary Leakage Curent versus Bias Voltage
-12
-10
-8
-6
-4
-2
0
2
4
6
8
-50 0 50 100 150 200 250
Bias (Volts)
Cur
rent
(nA
)
Leakage Curent versus Bias Voltage
-12
-10
-8
-6
-4
-2
0
2
4
6
8
-50 0 50 100 150 200 250
Bias (Volts)
Cur
rent
(nA
)
position [m]
sig
nal a.u
.
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
CERN Courier, Vol 43, Number 1, Jan 2003
3D DETECTORS AND ACTIVE EDGES
15 m InfraRed beam spotFWHM = 772 mEdge Al strip width = 16 m
INSENSITIVE EDGE (INCLUDING 16 m Al STRIP):
(813 - 772) / 2 = 21 m
Brunel, Hawaii, Stanford
EDGE SENSITIVITY <10 m
COLLECTION PATHS ~50 m
SPATIAL RESOLUTION 10-15 m
DEPLETION VOLTAGES < 10 V
DEPLETION VOLTAGES ~105 V at 1015n/cm2
SPEED AT RT 3.5 ns
AREA COVERAGE 3X3 cm2
SIGNAL AMPLITUDE 24 000 e before Irradiation
SIGNAL AMPLITUDE 15 000 e-
at 1015n/cm2
0
5
10
15
20
25
30
35
-400 -200 0 200 400 600 800 1000
Cu
rre
nt
[n
A]
Position [um]
0
5
10
15
20
25
30
35
-400 -200 0 200 400 600 800 1000
Cu
rre
nt
[n
A]
Position [um]
Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC
To measure the total cross section with ~ 1% precision
• total inelastic rate within 1 %
• extrapolation to t=0 within 0.3-0.4 %
Near Future plans:
• Optics optimization
• Further studies on the systematic
• Tests of different forward detectors