TOTEM Status Report

E. Bossini1,2 ,on behalf of the TOTEM collaboration

145th LHCC open session03/03/2021

1 Università di Pisa, Italy2 INFN – Pisa Section, Italy

OUTLINE:

Publication update Tunnel services and Si-strip detectors New T2 detector status

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Published on 05 February 2020

arXiv:2012.03981, CERN-EP-2020-236, submitted to PRL

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Published on 17 December 2020

arXiv:2102.06945, CERN-EP-2020-229, submitted to PRD

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pp cross-section @14 TeV

TOTEM pp cross-section measurements with the luminosity-independent method requires the simultaneous detection of the elastic and inelastic scattering events.

𝜎𝑡𝑜𝑡2 =

16𝜋

1 + 𝜌2ȁΤd𝑁𝑒𝑙 d𝑡 𝑡=0

𝑁𝑒𝑙 + 𝑁𝑖𝑛𝑒𝑙

LHC sector 45

ROMAN POTs(TOTEM/PPS)

LHC sector 56CMS central detector

nT2

Symmetric experimental setup w.r.t. the IP

Previous inelastic detectors T2 will be replaced by a new inelastic telescope based on scintillators (nT2) Elastic protons detected and

measured by the Si-strip detectors hosted in the TOTEM Roman Pots (RPOT)

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Main tunnel activities during LS2

Completed activities:

Detector Packages (DP) removed -> Si-strip ready for reinstallation in vertical RPOTs

RPOT “210 near” (qualified for high luminosity) successfully relocated @ “220 near”. New PPS timing detectors to be installed in “220 near” position – Sep 2019

Vertical realignment of the entire Long Straight Section LSS5 due to beam shift in Run3 – Sep 2019

Bake out sector 4-5 and 5-6 finished (sector valves closed) – Nov 2019

Upgrade of RPOT movement system – Nov 2019 Metrology for all RPOTs completed in joint

collaboration with BE-GM– Dec 2020.

RP station relocation

Q5

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TOTEM Position Control System Upgrade

Main upgrade of the TOTEM Position Control System:

• Replacement of PXI crate with new PXIe-1084 • Replacement of Real Time Controller with new PXIe-8840• Upgrade of 7 old PXI-FPGA 7833R (no more supported by

NI) with newer 7856 R• New FPGA works with different voltage level w.r.t. the LVDT

interlock interface. Interface adapted by EP-DT-DI

Status:

• Overall RPOT movement system commissioned in manual mode after FPGA upgrade

• New recommissioning performed in summer 2020• Calibration campaign performed • EP-DT is ready to test communication CCC/FESA/PXI/TOTEM

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Si-Strip status

Last used Si-Strips DPs uninstalled in Feb 2019 All 24 DPs stored in SX5 RP zone Permanently flushed by dry air from CMS line.

8 Si-Strips DPs are needed for installation on vertical RPOTs for Run3:

• In 2020 all 8 DPs passed the visual inspection and tests at IP5

• Few others DPs have been assigned as spares• Preparation of services (power distribution, DCS,

motor control) for the new DPs on schedule

• Migration of control software to CC7(8)/Qt5 completed and validated

Possible slot for reinstallation in the tunnel: week 42

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Installation Overview

nT2electronics

Fibers toelectronics

Passive detector in the beam pipe area.

Mockup for mechanical test and installation training

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Detection and light transport

145th LHCC open session

Grooved sigma design:

• Green WLS fiber from Kuraray• Mechanical splicing with clear fiber to

reduce light loss from tile to photo-sensor (2m)

• Completed light-tight design for each individual tile

Easy to replace tiles or clear fiber in the mechanical frame

Robust design for tiles and grooved WLS

Production of the nT2 quarters started

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Photo sensor

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Light detection with Hamamatsu S13361-6050:

• 16 MPPCs in a 4x4 matrix, can readout one nT2 quarter• Each MPPC has area of 6 mm, easy to align with 1 mm fiber.• Detection efficiency @ green ~ 30%

• Bias provided through Hamamatsu C11204-01, remotely controlled and monitored

Fibers

Connection block between board, MPPCs and optical fiber (final design)

Board slot with alignment pin

Test board developed:• 16 amplification channels (20 db). • Mechanics and biasing as in final design

Characterization of MPPC array Test of electro-optical chain

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Cosmic ray tests

3 scintillator tiles with final design dimension.

Final design from scintillator to MPPC :

• Scintillator size/mechanical support

• Internal fiber geometry• Fiber splicing/type/length• MPPC mechanical support• MPPC

All sources of light loss are included:

WLS collection, transport, detection.

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Cosmic ray tests

Trigger on top scintillator.Bottom scintillator as offline coincidence.

Three different thresholds to check stability of the result

MiddleThr(mV)

Top & Bottom

Triple coincidences

Efficiency

15 16884 16767 0.993

20 16884 16750 0.992

25 16884 16686 0.988

Signal amplitude in central tile

preliminary

Preliminary checks with cosmic rays show an detection efficiency ~99%.

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Electronics

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MPPC, biasing and signal digitization (NINO chip) located on a mezzanine board mounted on the TOTEM/PPS “Digitizer board”. Firmware (control, readout & trigger) partially derived from the TOTEM timing system.

First complete version ready for hardware test in ~2 months. Control software very compatible with TOTEM/PPS timing detector. Development of DQM and reconstruction software (integrated in CMSSW) ongoing

Existing electronics

New electronics

On schedule to have the detector ready in early 2022

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Conclusions

• TOTEM has recently published 2 new papers and 2 more have been submitted to journals. Related talks will be presented during the upcoming LHC Forward Physics meeting (link).

• Preparation for data taking @14TeV is ongoing:

RPOT infrastructure and services on schedule. Si-strip detector ready to be reinstalled.

nT2 is on schedule. Final design of the detector has been approved and production is ongoing. Electronics, firmware and software are well advanced.