Risto Orava

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The TOTEM Experiment
Risto Orava Department of Physical Sciences,
University of Helsinki and Helsinki Institute of
Physics on behalf of the TOTEM
Collaboration http//totem.web.cern.ch/Totem/
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Collaboration
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Measure (1) stot to 1

• Historical
• CERN Tradition (PS-ISR-SPS)
• Dispersion relation fit
• (logs)g , g2.2?0.3
• Current model predictions
• 100-130mb
• Aim of TOTEM
• 1 accuracy
• Absolute calibration of Luminosity

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Measure (2) the leading protons from elastic
soft diffractive scattering requires special
runs optics
Measure elastic protons with t ? 10-3 GeV2 ?
scattering angles of a few mrad

• At the IP small beam divergence ?q ?e / b? ?
  aim at large b(bO(1km))
• At the detector locations
• The optimum conditions
• parallel-to-point focussing planes (v 0)
• unique location-scattering angle relation
• large Leff ? scattered proton at measurable
• distance from the beam axis (?1mm)
• minimal beam emittance (e ?1mm rad)
• luminosity ?1028 cm-2 s-1
• With b 1540m parallel-to-focussing in both
  x- and y-planes simultaneously!

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Use the b 1540m optics for measuring the
elastics
at 220m
at 147m
Elastic Scattering
acceptance
b 1540 m
b 1100 m
Large t elastics measured with b18m
injection optics.
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Good acceptance and resolution in t requires
edge-active detectors accurately placed close
to the beam
50 acceptance vs. detector location
Uncertainty in acceptance vs. detector position
t0.004 GeV2 A44 t0.01 GeV2 A67
b1100m
t0.004 GeV2 A64 t0.01 GeV2 A78
b1550m
mm from physical to active edge of the detector
mms from physical detector edge to the beam

• Get the sensitive edge of the detector as close
  as possible
• 20 mm is sufficient resolution (beam divergence
  vs. resolution)
• Should know the detector location to better than
  20mm

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Total systematical uncertainty can be kept at
0.1 if detector position is know within 10mm
L1028 cm-2 s-1 run time 4 . 104 sec

• 10mm detector position
• uncertainty
• beam energy uncertainty
• dominates

over-all systematical uncertainty 0.1 Account
for beam angular divergence crossing angle,
optical functions, beam position, detector
position resolution, alignement, backgrounds
(beam halo, DPE)
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Several options for detecting the leading protons
CMS Tracker Hybrid
3cm
Thermal analysis
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Basic detector requirements are set by the LHC
environment and active edge

• High and stable efficiency near the edge facing
  the beam, edge defined to lt 10 mm (present LHC
  designs ?0.5mm)
• Detector size 3x4 cm2
• Spatial resolution 20 mm
• Systematics 20 mm
• Moderate radiation tolerance
• (1014 1 MeV neutrons /cm2 equivalent)

Detector choices

• cut planar cold Si strip detectors
• cut planar warm Si strip detectors
• planar edge-active (warm) Si strip det
• Si strip detector with 3D electrodes active edge

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Cryogenic Si-detectors

• Planar Si strip detectors
• operated at cryogenic temperatures (110-130 K)
• exhibit
• low bias voltage
• radiation hardness

Z. Li et al, "Electrical and TCT characterization
of edgeless Si detector diced with different
methods", IEEE NSS Proc., San Diego, Nov. 2001
active edge starts at ?20mm
Novel planar technologies
For room temperature operation Extra n or p
ring at the edge prevents current C Simulation,
test structures, beam tests being carried out
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PLANAR-3D Si-DETECTOR WITH ACTIVE EDGE
Brunel, Hawaii, Stanford
TRADITIONAL PLANAR DETECTOR TRENCH FILLED WITH
POLYSILICON
p Al
E-field
n Al
i
n Al
signal a.u.
position mm
Edge sensitivity 20 mm
Leakage current 6nA at 200V
new test structures at SEF/VTT/Finland
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Si-detectors with 3D electrode structures and
active edges is the ultimate goal
3D DETECTORS AND ACTIVE EDGES
Brunel, Hawaii, Stanford

• EDGE SENSITIVITY lt10 mm
• COLLECTION PATHS 50 mm
• SPATIAL RESOLUTION 10-15 mm
• DEPLETION VOLTAGES lt 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

Brunel, Hawaii, Stanford

• INSENSITIVE EDGE
• (INCLUDING 16 mm
• Al STRIP)
• (813 - 772) / 2 21 mm

SEFO/VTT-Finland now has 1st test structures

• CERN Courier, Vol 43, Number 1, Jan 2003

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Pots and pans for leading proton measurement...

• Basic requirements at the LHC
• limited space limited access
• light, compact structures for reducing
  backgrounds activation
• UHV to be preserved low-outgassing rates,
  bake-out at 200
• degrees
• active detector edge to be placed accurately
  close to the beam
• (O(1mm))
• protection from the RF pick-up, RF impedance
  budget low
• heat produced by the detectors read-out
  electronics to be
• dissipated outside the secondary vacuum
  enclosures
• radiation hard technologies materials required

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The Roman Pots
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Inside the Roman Pot
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Interfaces
PCB cards
Cooling
Connectors
Flat cables
D-Connector
Flange with double sided D-Connectors
Flange with feeding through PCB cards
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Compensation bellow
Sticking them in...
Pot
Lever Arm
Capacitive sensor
Roman Pot Device (Second Version)
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A novel detector for measuring the leading
protons - the Microstation - is designed
to comply with the LHC requirements.

• a compact and light detector system high
  efficiency,
• minimal disturbance to the machine close-by
  detectors
• integrated with the beam vacuum chamber
  (detector
• moving mechanism enclosed in separate vacuum)
• geometry and materials compatible with the
  machine
• requirements
• can use small high precision solid state
  (ultrasonic) non-
• magnetic motors for high accuracy and
  repeatability in
• sensor movements
• robust and reliable to operate
• edge active Si detector technology being
  developed

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Microstation
Inch worm motor
Emergency actuator
6cm
Inner tube for rf fitting
Space for cables and cooling link
Detector
Space for encoder
Note The secondary vacuum arrangement is not
shown.
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Microstation, Secondary Vacuum Implementation
Detector
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Microstation, Secondary Vacuum Implementation
Motor(s) and positioning rods, (depending on
selection of the motor type also gears and
bearings
Support
Detector bellows
rf fitting
Detector
Detector frame
Detector frame cavity

• Motor holder
• -stiff contact with motor
• stiff contact with support
• loose contact with secondary vacuum wall

Secondary vacuum wall
Matti Ryynänen KOPERO Ltd 1-03
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Integration to the machine
Collimator
BPM
QRL
TAN
Racks
Roman Pot Station (made of two RP devices)
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(No Transcript)
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Interactions with the machine

• Design and construction of the Roman pots/
  Microstations together with EST
• Tests and production of the prototypes
• Risk analysis of the secondary vacuum and of the
  operation
• LHC impedance requirements
• Radio frequency shielding
• Integration and services into the tunnel
• Choice of the cryogenic cooling system for the
  Silicon detectors
• LHC vacuum requirements NEG coating and
  bake-out at 300 K

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Forward inelastic detectors T1 T2

• T1 5 planes of CSC
• coverage 3.1 lt ? lt 4.7 full azimuthal
• spatial resolution better than 0.5 mm

• T2 5 planes of silicon/GEM detectors
• coverage 5.3 lt ? lt 6.7 full azimuthal
• spatial resolution better than 20 ?m

IP
7.5 m
3.0 m
T1 detector
HF
Castor
? IP
T2 detector
13.6 m
0.4 m
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Measurement of the inelastic rate

• T1T2the forward leading proton detectors allow
  fully inclusive trigger
• DD MinBias -gt double arm inelastic trigger
• SD -gt single arm inelastic single arm leading
  proton
• Elastics DPE -gt double arm leading proton
  trigger
• Vertex reconstruction necessary for disentangling
  beam-beam events from background

Event loss lt 2 Uncertainty lt 1
Diffraction
TOTEM CMS -gt a large acceptance detector.

• 90 of all diffractive protons detected
  (high ??)

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Total TOTEM/CMS acceptance (b1540m)
RPs
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Total TOTEM/CMS acceptance (b18m)
RPs
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Double Pomeron Exchange
M (GeV) x1 x2
CMS/TOTEM collaboration for high luminosity
diffractive physics b 0.5 m
-gt For details see talk by K. Österberg
Trigger via Roman pots x gt 2.5 10-2 Trigger via
rapidity gap x lt 2.5 10-2
xDp/p proton momentum loss
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Running scenario

• Total Cross Section and Elastic Scattering
• Several 1-2 day runs with high (1540m) b
• Several 1-2 day runs with b 18 m for large-t
  elastic scattering
• Diffraction
• Runs with CMS with high b for L 1028cm-2 s-1
• Runs with CMS with b 0.5 m for L lt 1033cm-2
  s-1

Plans

• Test of silicon detectors (2003-04)
• Roman pot prototype by end 2003 ?
• Technical Design Report by end 2003
• CMS/TOTEM collaboration for high luminosity
  diffraction