1. TOTEM experiment at the LHC
TOTEM physics
T1&T2 detector
Roman Pot First results
Conclusions
Joachim Baechler
CERN PH-Department
on behalf of the TOTEM collaboration
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

2. TOTEM physics Total cross section Elastic cross section
 Special LHC settings optics luminosity
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

3. - Measurement of total cross section
Forward multiplicity
Diffractive physics
TOTEM detectors integrated in CMS (T1, T2)
TOTEM detectors integrated in LHC (RP)
Using luminosity from CMS
Luminosity independent
ρ parameter from compete fit
TOTEM physics program:
TOTEM (stand alone) & TOTEM+CMS
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

4. 12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

5. TOTEM detector system CHALLENGE T1 & T2 integrated in CMS
Protons are transported in LHC beam-pipe from IP 5 to the Roman Pot stations
Roman Pot : detector enters for measurement
inside the LHC beam tube
CHALLENGE
TOTEM has interface to
CMS and LHC
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)
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

6. TOTEM T1 detector - CSC (integrated in CMS)
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

7. T1 detector system installed during LHC winter shutdown 2010/2011
CMS
T1 in SPS-H8
beam line
T1 detector
before insertion
in CMS
T1 detector
After insertion
in CMS
Successfully tested with pion and muon beams
Both arms were completely assembled and equipped in the test beam line H8
Both arms installed in CMS Minimal distance to beam pipe : ~25 mm
Fully operational since spring 2011
beam pipe
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

8. T1 performances
Chamber efficiency
Eff [%] +1
Plane +2 +3 +4 +5 –5 –4 –3 –2 –1
(includes read-out effects)
Each hit is reconstructed as triple coincidence of one wire and two strips signals
Track reconstruction requires hits in 4 out of 5 CSC planes
S. Minutoli : Front End, Trigger, DAQ and Data Management - Poster Session:
The electronics system of the TOTEM T1 telescope
“Raw” η distribution
zvertex
s = 3.4 cm
yvertex
xvertex
σ = 110 cm
Vertex
reconstruction
No correction for efficiency, acceptance, resolution
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

9. T2 Detector (triple GEM)
Triggering and Tracking Capabilities
h coverage:
j coverage: 360o
Readout Granularity:
dr ≈ 400mm [pitch]
dj = 2.9o [pitch]
4 quarters with 10 detectors aligned each
Number of tracks in inelastic 7 TeV ~ 100
Area of T2 ~ 103 cm2
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

10. TOTEM T2(GEM detector) in CMS
open closed
5.3 < || < 6.6
10 detector planes on each side of the IP to cope with high particle fluxes.
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

11. TRIPLE GEM - T2 (E. Oliveri)
Totem Triple GEM Cluster distribution
Ar/CO2 70/30
H.V. Idivider=720mA
(E. Oliveri)
Strips (r):
512 strips
2 j sectors of 256 each
400mm pitch, 80mm width
mean cluster size(*) ≈ 2.5-3
Pads ( triggering & j ):
1560 pads
65 j sectors of 24 each
dj = 2.9o, dh = 0.05
mean cluster size (*) ≈
T2 integrated luminosity is on µb-1, nb-1 scale
Collected electron density per 1 fb-1 ~ 3.5 mC/mm2
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

12. TOTEM VFAT
Triggering and tracking synchronous front-end ASIC designed primary for the TOTEM experiment and characterized by:
Preamplifier-shaper-comparator readout chains (128) to detect signals above a programmable threshold.
Fast-OR lines (up to 8) that merge channels of programmable sectors to provide a trigger signal.
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

13. Physics results T2 dNCh / dh
Measurement of the forward charged particle pseudorapidity density in pp collisions at √s = 7 TeV with the TOTEM experiment CERN-PH-EP ;
T2 dNCh / dh
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

14. TOTEM Roman Pots at LHC at +/- 147m and +/- 220 m from IP5
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

15. Roman Pot edgeless Si-sensor
Physics requirement to measure as close
as possible to the LHC beam
Technical specification of RP Si detector
strips – pitch : 66 µm
#strips/sensor: 512
Wafer thickness : 300 µm
5 pairs of planes/RP
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

16. Hybrid and assembly “champignon” Assembly of 10 detectors
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

17. TOTEM Roman Pots installed at LHC
Roman Pot unit
with
motor system (step size: 5 µm)
Separation
of high LHC vacuum
from detector vacuum
Secondary vacuum ~ 20mbar Temp : -25 0C
LHC beam-pipe
RP mother board: interface Si- detectors to outside world: Signal, Trigger,HV,LV
Hosts Radmon sensor and PT 100
Roman Pot
parking position
Roman Pot data taking position
RP mother board
Typical beam size:
540 µm / 850 µm
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

18. Roman Pot beam based alignment
Insertion of RPs complicated and dangerous operation :
Risk of beam dump and
damage of sensors
TOTEM uses and adopted the LHC collimator control application
Complex interlock logic (TOTEM-LHC)
All movement operations are done form the LHC-CCC
Both Roman Pots (top and bottom) are touching the beam edge :
Both pots are the same distance (expressed in sigma) from the beam centre as the collimator
 Alignment of the RP windows relative to the beam
Silicon sensor positions (relative to each other and to the beam) aligned by software methods
After this exercise the RPs can be inserted without new alignment
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

19. Physics results (elastic scattering)
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

20. p-p elastic scattering
p-p elastic scattering differential cross-section
Acceptance correction
Resolution
Efficiency
Background
External luminosity measurement
t limit= 2*10-2 GeV2
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

21. Radiation load on TOTEM detectors
Active and passive RadMon sensors mounted on RP – T1 – T2 detector
for TID and NIEL measurement T2 RP
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

22. EM coupling of RP Cooling of RP was switched off
The temperature in the Roman Pot increases due to the EM coupling with the LHC
-> cooling of RPs is mandatory when LHC beam is injected
-> modification of evaporative cooling system by integrating a safety mode to operate above dew point in case of vacuum problem
Cooling of RP was switched off
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

23. Electrical trigger TOTEM RP (220m) -> CMS
Repeater Card (for the LVDS signals)
This card receives the 16 LVDS signals, it recovers the amplitude and compensates the frequency dependent attenuation of the cable.
Propagation delay is ~1.2 ns per card,
Filter tuned for a 70 m long cable segment and 40 MHz clock
Electrical trigger installed during LHC technical stop 2011/2012 Commissioned with first LHC beam in 2012
2x 16bit per RP (384bits on total)
8x 70 m of industrial cable per RP (6720m in total)
96 repeaters, 24 repeaters for patch panel (12 isolation cards)
J. Kopal, PhD thesis under preparation
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

24. Conclusions
First physics results published on p-p elastic scattering, total p-p cross section and forward charged particle pseudorapidity density at √s = 7 TeV
EPL, 95 (2011) 41001
EPL, 96 (2011) 21002
EPL, 98 (2012) 31002
All TOTEM sub detectors are installed and fully operational (T1, T2, RP +/- 147m, RP+/- 220 m)
All detectors work according to specifications and were operated at LHC (special runs) – - RP were operated at full LHC luminosity at 20 σ
Combined runs with T1, T2 and Roman Pots successfully done
Installation and commissioning of electrical trigger (RP 220 m) in technical stop 2011/ > allows to trigger CMS for common runs
Combined runs with CMS (Heavy Ions, p-p low luminosity) done in 2011 and 2012
The radiation load is not limiting the detector performance
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

25. Outlook
RP 220 m –> ß* = 0.6 m
Forward physics at high luminosity requires ultra radiation hard Si pixel detectors (>1015 p/cm2) and timing information (< 10 ps)
-> Integration of timing detector in Roman Pot detectors at 220m is under study
The Si based picosecond timing detector (ongoing developments
at Princeton and Rockefeller) is of interest for the RP project.
(WORKSHOP ON TIMING DETECTORS - NOVEMBER 29, 30, DECEMBER , S, White)
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

26. Backup slides
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

27. Pitch/√12 = 0.4mm/ √12 =0.115mm
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

28. RP performance Signal = 25,000 e-
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

29. 12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

30. 12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

31. 12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler

32. Physics results (2)
Primary particle definition: charged particle with > 0.3*10-10 s & pt > 40 MeV/c
With all requirements:
- primary track efficiency ~ 80%
- fraction of primary tracks in the “peak” ~ 75%-90% ( dependent)
12/4/2018
12th Pisa Meeting on Advanced Detectors May 2012 Isola d'Elba , Italy Joachim Baechler