The TOTEM experiment

The TOTEM experiment
Status and upgrade project
Nicola Turini 27-9-2012
ρ parameter from Compete fit
CHALLENGE
TOTEM has interface to
CMS and LHC
Protons are transported in LHC beam-pipe from
IP 5 to the Roman Pot stations
Roman Pot: detector enters
inside the LHC beam tube
T1
5 planes of CSC
Chambers (wire &
cathode strips
 T1 & T2 integrated in CMS
 Roman Pot integrated in LHC
T2
10 planes of GEM
Chambers
(pads&strips)
2
•
•
•
Aprile 2012: Engineering Run (Allineamento RPs) - Trigger CMS<>TOTEM Sincronizzazione Dati OK
Maggio 2012: Run basso pile-up, 8M eventi (RPs non inserite),
scambio di
triggers: TOTEM -> CMS: trigger menu -> TOTEM , entrambi gli esperimenti hanno
registrato gli stessi eventi. Analisi in corso.
CMS trigger con RPs ora possibile grazie a nuovo trigger elettrico (entro latency L1 CMS)
+ grande copertura CMS+T1+T2 (- 6.5 < h < +6.5)
– dNch/dh su completo range con stesso min. bias trigger
– sezione d’urto inelastica
– rapidity gap
– jets – underlying event – energy flow nella regione in avanti
– central, single diffraction: trigger – CMS jets + TOTEM RPs: 1 o 2 protoni
3
Run speciali nel 2012
•Run b*=0.6m, low pileup ottenuto separando i due fasci con CMS:
• Rp non inserite solo studio del dN/dh
•Run b*=0.6m, alta intensità ~1400 bunches, standard injection + CMS:
•Solo RP orizzontali inserite e rivelatori inelastici off:
•z >2/3 %, ogni t accessibile
•Alta luminosità, masse relativamente alte accessibili
•Run b*=90m, 112 bunches, pileup~0.05
•Totem + CMS
•Accettanza per i protoni per ogni z , |t|>0.02 GeV2
•Soft, medium, hard diffraction
•elastic and total cross section
•Run b*=1000m, 2/3 bunches:
•Low t elastic scattering
•Determinazione del parametro r
•Run Pa, RP lato protoni inserite e rivelatori inelastici + CMS:
•Scattering protoni
•Ultra Periferic interactions.
Analisi dati 2010/2011
TOTEM ha pubblicato a √s = 7 TeV :
1)
2)
3)
scattering elastico (dati 2010) EPL 95 (2011) 41001,
sezione d’urto totale p-p (dati 6/2011) EPL 96 (2011) 21002,
forward charged particle pseudorapidity density (dati 5/2011) EPL 98 (2012) 31002

Dal run speciale a b*=90m di Ottobre 2011 (RPs a 4.8sbeam) sono in preparazione 3
pubblicazioni:
P1. Measurement of proton-proton elastic scattering and total cross-section
New elastic differential cross-section measurement down to t-values of 5 10 -3 GeV2
Compared to our previous publication EPL96:
– 15 x higher statistics
– |t|min ~ 5 10 -3 GeV2
91% of cross-section observed (only 67% before)
P2. Measurement of the inelastic pp cross-section
Tracks in both arms: Non-diffractive minimum bias & double diffraction
Tracks in one arm: Mainly single diffraction with MX>3.4 GeV/c2
After corrections for trigger efficiency (2.3%), track reconstruction efficiency (1%), beam-gas bkgd (0.5%),
pile-up (1.5%):
sinelastic, T2 visible = 69.7 ± 0.1 (stat) ± 0.7 (syst) ± 2.8 (lumi) mb
sinelastic, T2 visible
sinelastic, |h|<6.5
After corrections for non visible events (Tracks in T1 & T2 empty), Rapidity gap covering T2:
sinelastic,|h|<6.5 = 71.0 ± 0.1 (stat) ± 0.7 (syst) ± 2.8 (lumi) mb
sinelastic, h<6.5
sinelastic
Several models studied, correction for low mass diffraction based on QGSJET-II-4 ~ 3.7% ± 2% (syst),
imposing observed 2hemisphere/1hemisphere event ratio & taking into account seen “secondaries”
sinelastic = 73.7 ± 0.1 (stat) ± 1.7 (syst) ± 2.9 (lumi) mb
7
P3. Luminosity-independent measurements of
total, elastic and inelastic cross-sections
Complementary measurements:
•
•
•
to control and reduce systematic effects
to remove dependence on luminosity
to remove dependence on the r parameter
Proton-Proton Cross-Sections @LHC: 4 Methods
1.
Low_L(CMS) + Elastic + Optical T.
depends on CMS luminosity for low-L bunches & elastic efficiencies & r
2.
High_L(CMS) + Elastic + Optical T.
checks the CMS luminosity for high-L vs low-L bunches
3.
High_L(CMS) + Elastic + Inelastic
sTOT = sEL + sINEL
minimizes dependence on elastic efficiencies and no dependence on r
4.
(L-independent) + Elastic + Inelastic + Optical T.
eliminates dependence on luminosity
8
pp Total Cross-Sections @LHC √s=7TeV
1. sTOT = 98.3 mb ± 2.2 mb
2.0
2. sTOT = 98.6 mb ± 2.5
mb
2.2
3. sTOT = 99.1 mb ± 4.3 mb
4. sTOT = 98.1 mb ± 2.7
mb
2.2
Diffractive forward protons @ RPs
Dispersion shifts diffractive protons in
the horizontal direction
Low b*: 0.5 – 2 m
• For low-b* optics Lx, Ly are low
• vx, vy are not critical because
of small IP beam size
b*= 90 m
• Lx=0, Ly is large
• beam s = 212 µm → vx, vy important
(deterioration of rec. resolution)
Upgrade Program during LS1
(High beta special runs)
• The baseline Upgrade program is a consolidation of
the present hardware towards the repetition of the
present measurements at higher energies.
– RP overhauling + spare production (no radiation damage
seen till now)
– T1 overhauling (some VFAT replacement)
– T2 some electronics development to ensure a better
functionality.
– DAQ some electronics development to have a simpler and
efficient system.
T1
• The detector have to be removed and put on
surface in a controlled area. We need the gas
flow in the detector.
• Some VFAT has been damaged and have to be
replaced
• Some power problem seen at higher track
multiplicity have to be investigated and solved
T2
• The front-end card, named 11th card, have to be redone. The
present one (4 in total) is very complicated and in a
technology (multiwire) that is giving troubles (lines that
disconnect with time)
• The actual signal cables have to be removed (8% of broken
lines) and a simpler and closer to the detector data
transmission card have to be produced
• A new HV divider have to be produced.
– Faster electron collection with different voltage gaps between and on
the GEM foils
– Some gain limitation at higher track multiplicity have to be solved
DAQ
• Currently the DAQ is performed in four different VME
crates to ensure enough bandwidth.
• We foresee a simpler system with one crate (SRS)
directly connected via Ethernet to the central DAQ
computer.
• For common CMS-Totem runs a complete integration
in their system is under development (Slink -> FRL).
DAQ Upgrade
OptoRX + SRS Inteface
High luminosity program
Low Beta runs
• The major problem is the large pileup that is mixing up different
elastic and inelastic processes in one event
• The possibility to get the primary vertex tag in the forward region
is possible only trough TOF measurements.
• We are starting an R&D program to find out the best hardware to
ensure enough time resolution in the Horizontal Pots to
disentangle the primary vertexes (10 ps resolution).
– Cherenkov
– APD
– SiPm
• Fast TDCs and/or Sampler under investigation.
High luminosity program
Low Beta runs
• Multiple track reconstruction due to the pileup
– Si Pixel
– 3D
– More planes
• Radiation damage
– 3D
– P over N silicon strips
Totem + CMS
• The present upgrade proposal is a major
project that requires the collaboration of CMS
and TOTEM groups.
• The joint effort between the two
collaborations is under discussion.
• Some step has already been done towards a
common project.
TOTEM Roman Pots installed at LHC
Roman Pot unit
with
motor system
(step size: 5 µm)
Separation
of high LHC vacuum
from detector vacuum
LHC beam-pipe
Roman Pot
parking position
Roman Pot
data taking position
RP mother board
Typical beam size:
540 µm / 850 µm
Secondary vacuum ~ 20mbar
Temp : -25 0C
RP mother board:
interface Sidetectors to
outside world:
Signal,
Trigger,HV,LV
Hosts Radmon
sensor and PT
100
20
220m Pots
New Horizontal Pots stations are under evaluation
220m Pots
New Collimator in front of Q6
Inelastic detector with ToF
• We are investigating the possibility to insert ToF planes in the
T2 region.
• We can disentangle primary vertexes from ToF measurement
of primary particle (selected with the present algorithm and
spatial resolution)
• The same hardware used in the Pots stations can be
assembled in front of T2
• Possible to recover double arm vertex position combining Pots
and T2 ToF information.
Backup
Towards a CMS – TOTEM Upgrade synergy
Event display N=20 (assuming independent Vtx-reco and the current T2-track
resolution)
- Tracking capability at high luminosity is assumed.
- Reconstruction performed assuming no track overlap from different vertexes and using the default T2
reconstruction.
-Only double arm
events displayed
-Primary event selection
efficiency ~85%.
Single vertex spatial resolution
(averaged peak-signal used)
 Single vertex can be tagged
with a good spatial resolution (~
0.1 cm).