LHCb upgrade: Status of the Scintillating Fiber tracker · 2018. 11. 15. · LHCb SciFi Tracker, 12/03/2013 Detector feasibility studies • First studies focussed on:-radiation hardness

LHCb upgrade:Status of the Scintillating Fiber tracker

Fred Blanc (EPFL)for the LHCb collaboration

LHCC Detector Upgrade ReviewCERN

12/03/2013

LHCb SciFi Tracker, 12/03/2013

LHCb detector• LHCb upgrade: replace several detectors, and R/O electronics• Discuss here the replacement of the tracker, downstream of the magnet

2

pp interaction point

Downstream Tracker


Tracker upgrade: detector layout• Two options are being considered:

• Scintillating fiber (SciFi) is a new technology in LHCb⇒ can a SciFi tracker fulfill the performance requirements?⇒ will the SciFi technology perform as required after the radiation dose received in the LHCb upgrade (50fb-1)?

3

Straw tubes(“Outer Tracker”)

Silicon strips(“Inner Tracker”)

Scintillating fiber(“Central Tracker”)

Silicon strips + Straw tubes Scintillating fibers + Straw tubes3m

2.5m

2.5m


Main SciFi detector features• 250µm diameter scintillating fibers- arranged in multiple layers for sufficient light collection

• Cover the acceptance with 2.5m long fibers- mirror at the center (beam pipe height)- light detected outside the acceptance⇒ minimize “inactive” material in the acceptance

- vertical (x) and stereo (u&v) layers• readout with multi-channel Silicon photo-multipliers (SiPM)

• Readout: 40MHz front-end electronics

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SiPM active area optimization

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250 !m dead region

Present situation: SiPM with 128 channel, made of two chips placed aside.

!"#$%$&'($ )

With ~250 !m fibers amplitude reduced but still " zero


Signal clusters in SiPMs

5

mean position

1. Particle creates photons in the fibers

2. Pixel (red squares) detect photons propagated through the fibers

Multi pixels in each detector channel

pos

signal


Detector requirements

• High hit detection efficiency (≥ 98−99%)• Spatial hit resolution at the level of 60−100µm• Minimize material in the acceptance• Readout electronics to operate at 40MHz• Rate of reconstructed noise clusters < ~ 2MHz / 128-channels

• The above requirements must be fulfilled over the full lifetime of the experiment (up to 50fb−1)

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Detector feasibility studies• First studies focussed on:- radiation hardness of SiPMs and fibers- identification of solutions for the Front-End electronics- building 2.5m-long fiber modules- various aspects of infrastructure

and integration (e.g. cooling)

• These studies were the subjectof an internal LHCb review- described in LHCB-INT-2013-004

(+ supporting notes)

- “viability assessment” review workshopon 7th February, 2013

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LHCb-INT-2013-004January 24, 2013

Viability Assessment of aScintillating Fibre Tracker for the

LHCb Upgrade

A. Bay10, F. Blanc10, S. Bruggisser10, O. Callot2, H. Chanal1 E. Cogneras1, A. Comerma-Montells8, M. Deckenho↵3, G. Decreuse9, M. Demmer3, V. Egorychev5, R. Ekelhof3,D. Gascon8, A. Golutvin11,5,9, E. Graugés8, O. Grünberg12, E. Gushchin6, Yu. Guz7,G. Haefeli10, P. Jaton10, C. Joram9, M. Karacson9, B. Leverington4, R. Lindner9, N. Lopez-March10, T. Nakada10, M. Patel11, P. Perret1, A. Puig Navarro10, B. Rakotomiaramanana10,J. Rouvinet10, T. Savidge11, O. Schneider10, T. Schneider9 P. Shatalov5, B. Spaan3,E. Thomas9, G. Veneziano10, U. Uwer4, Z Xu10, H. Yu10.

1Université Blaise Pascal, Clermont-Ferrand, France, 2LAL, Université Paris-Sud, Orsay, France,3Technische Universität Dortmund, Germany, 4Ruprecht-Karls-Universität Heidelberg, Germany, 5ITEP,

Moscow, Russia, 6INR RAN, Moscow, Russia, 7IHEP, Protvino, Russia, 8Universitat de Barcelona,

Spain, 9CERN, Geneva, Switzerland, 10EPFL, Lausanne, Switzerland, 11Imperial College London, United

Kingdom, 12Universität Rostock, Germany

Abstract

This document describes the parameters and qualities of scintillating fibres and siliconphotodetectors for a central tracking detector for the LHCb upgrade and discusses theviability of the proposals for a tracking detector set forth in the Framework TechnicalDesign Report and Letter of Intent. It summarizes experimental, simulation andliterature studies to assess the viability of the baseline components with a particularemphasis being put on their tolerance to damage from radiation. The specificationsof the fibre and photodetector will have strong impact on the design of the front-end electronics and vice versa. Some of the results for this are also reported here.Finally, we will present a conclusion based on the results of our studies and othercollaborations, regarding the suitability of a scintillating fibre based tracker with aSilicon Photo-Multiplier (SiPM) read out in the higher luminosity environment ofthe upgrade scenario.


Review mandate

• Referees: Carmelo D’Ambrosio Jacques Lefrançois Marcel Merk Iouri Musienko

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The referees are asked to assess the viability of the proposed SciFi+SiPM solution for the LHCb upgrade downstream tracker. The following questions and points are to be addressed:

1. Is the performance after irradiation of the scintillating fibers and SiPMs sufficiently well understood to make useful predictions after an integrated luminosity of 50fb-1 in the LHCb upgrade?

2. Are the proposed solutions for the Front-End electronics able to handle the degraded signal following the fiber and SiPM irradiation?

3. Does the proposed detector meet the tracking performance requirements as determined from simulation?

4. In case the SciFi+SiPM solution is considered a viable solution from radiation hardness point of view, the reviewers are asked to provide a list of recommendations in view of the Technical Design Report.


LHCb upgrade: radiation environment

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Dose• 10cm x 10cm x 0.07cm grid

situated at z= 783cm, ranges from x[-350,350]cm y[-500,500]cm

SiPM position ( ±250cm)

1D projection on the y-axis for x[0,10]

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

-500 -400 -300 -200 -100 0 100 200 300 400 500

Do

se (

Gy)

Y(cm)

Dose (Gy) for x[0,10] cm and 50fb-1

• Using the cartesian grid the peak dose is aprox. 1kGy

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Conclusions

• Ionizing DOSE: At a position of 9cm aprox. from the beam axis, the peak dose is about 26kGy and average dose over the second and first rings gives 23kGy (10% stat. error)

• Neutron fluence could be reduced by a factor more than two for 1MeV neutrons using a shielding 10cm-thick

• 1MeV neutron-equivalent fluence: At a position of ±250cm, the neq fluence is 6x1011 per cm2

SiPM rad. environment

Fibers rad. environment

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FLUKA sim

ulations


Scintillating fiber radiation hardness• Baseline fiber: Kuraray SCSF-78MJ• Damage due to radiations found to increase logarithmically

with the dose

• Projected relative light yield loss:(without mirror & without timing cut)

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1507/02/2013

Simple modeled light yield

Folding in Hara et al.'s dose/attenuation model with the FLUKA simulation and the attenuation curve of a non-irradiated fibre one can estimate the behavior of the fibre's light yield:

Non-irradiated fibre (0.46)

Damaged fibre after 50fb-1 (0.28)

40% yield loss


Light yield loss: with mirror and timing cut

• Effect of mirror and timing cut is to reduce light yield spread for all hits along the 2.5m long fiber

11

Olivier Callot

Attenuation versus y position ( x = 1 m means almost no radiation effect )

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4

x = 0 x = 1 m x = 0 no mirror x = 1m no mirror

13 December 2012 FT software 22


Detector performance from simulation• Tracking on simulated data has been used to evaluate the

performance of the SciFi tracker:

• Estimated level of acceptablenoise clusters: ~2MHz

• Fibers must be straightover their full length⇒ engineering challenge

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Olivier Callot

Summary of tracking performance At top luminosity, performance is similar to now

5 times more luminosity Mu from 1.7 to 4, and energy 8 -> 14 TeV. Efficiency similar Ghost rate and speed a bit worse.

Seeding is possible

Improved software is needed for speed.

We can not decrease the number of layer to 10 This becomes sensitive to any detector problem

A similar stereo angle is OK, around 100 mrad

7 February 2013 Simulation of the Fibre Tracker 12

Olivier Callot

Misalignment in Z

0

5

10

15

20

25

30

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Ghost Inefficiency Inefficiency > 5 GeV

13 December 2012 FT software 18

[mm]


Simulation of the hit detection efficiency

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1 2

1) Efficiency 99% with 2.5PE seed cut and 4.5PE sum cut, 16PE required , fC=2MHz

2) Efficiency 99% with 2.0PE seed cut and 4PE sum cut, 14PE required, fC=5MHz

Note: This simulation needs to be verified further with the data from test beam and cosmics tests.

SiPM radiation hardness• So far, considered two SiPM manufacturers: Hamamatsu and KETEK• Maximize the hit detection efficiency, while keeping the cluster

noise at an acceptable level (< ~2MHz / 128-channels)

• Noise controlled by:- shielding, cooling,

pixel-pixel cross-talk,integration time

• Results:- noise can be kept

below 2MHz

- photon detection efficiency:OK for the KETEK SiPM,and too low for Hamamatsu SiPM

• On-going R&D is expected to improve significantly the performance of the Hamamatsu detector

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SiPM: compilation of possible improvements

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Expectation from new detectors and improved fiber module

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Hamamatsu: Improved x-talk and after-pulsing, 2% or below Thin film resistors and new pixel layout can increase PDE from 30% to almost 60% (level of KETEK) With lower x-talk and after-pulsing, thresholds for noise suppression can be lowered to point 2) , improvement of S/N

New signal: Sirrad= 13.6PE

KETEK Green light shifted sensitivity (+10%)

New signal: Sirrad=10.5-14.0PE

Use fiber mat with 6 fiber layers increases the signal by 20%. Optical couplings can be improved, might gain 10%.

Hamamatsu: New signal: Sirrad= 17.7PE

KETEK New signal: Sirrad=13.7-18.2PE

+ possibility to replace the SiPMs in central region


7 February 2013 Modules & Integration 8

Fiber mats (2/2)

Fiber mat production

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• Fibers are wound on a 2.5m circumference wheel• Tension and quality control system• Each layer glued to the previous layer• Development ongoing


SiPM cooling (−50ºC)• Considering several cooling systems for SiPMs

1. liquid (single- or 2-phase)

2. thermoelectric cooling

3. chilled air cooling

4. cooling through the PCB

• Thermal analysis of the various options in progress16

Graphite heat spreader Optional cold plate

2-stageTE module

Solder/glue

Thermoelectric cooling

Example: eight [2-3W] Peltiers per module

TE Technology’s TE-2-(31-12)-1.0

Thermal pad

FPCB is not cooled, must be insulated

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4 mm

6 mm

10 mm

8 mm

2.8W dissipated, 0.3W cooling

Sci-Fi Tracker Meeting, CERN 14-Feb-2013 P.Gorbounov

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thermal pad

• SiPM is encaplulated into “cold spreaders”

• The FPCB is cooled • The cooling structure is flat and

linear, easy to insulate (Armaflex, ceramic paint)

• The gap filler (0.2-0.5 mm) prevents from sheer stresses

• SiPM + cooling = block

refrigerant at T=0 -50oC (FC, HFC or HCFC, like R22 or R134a)

Inner insulation

Outer insulation

Liquid cooling (single- or 2-phase)

FPCB is cooled

5

Alignment pin

Sci-Fi Tracker Meeting, CERN 14-Feb-2013 P.Gorbounov

Fibers


Detector layout and integration (in progress)

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GLOBAL DESIGN, INTEGRATION CONSTRAINTS

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GLOBAL DESIGN, INTEGRATION CONSTRAINTS

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Conclusion (I): results of the review• Damage from irradiation to fibers and SiPMs has been studied- find that light yield from current fibers, and PDE from current SiPM are

at the limit of the requirements for the LHCb upgrade

- the needed performance will be reached with the expected improvements to the technology (fibers and SiPM), and with design choices (5→6 layers; cooling; possibility to replace SiPM; ...)

⇒ the SciFi detector is viable from the point of view of radiation damage

• Results of the review process:- the referees concluded that there is no show-stopper from the point of

view of radiation in using scintillating fibers and SiPMs in the upgrade of the LHCb tracker

- the referees made recommendations for the next steps of the R&D and detector design (including front-end electronics, simulation studies, detector layout, etc...)

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Conclusion (II): next steps• Based on the results of the review, the LHCb Technical Board

concluded that the scintillating fibers and SiPMs are a viable technology option for the LHCb upgrade tracker system

• The next steps towards a Technical Design Report are in preparation:

1. continuation of the SciFi and SiPM R&D

2. construction of a first detector module (module 0) with all functionalities

- challenging engineering R&D(e.g. fiber mat production, integration of the cooling, ...)

3. design of the front-end electronics

- multiple solutions are being considered- many challenges (e.g. on critical path for chip development)

4. design of the global detector layout

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Documents

LHCb upgrade: Status of the Scintillating Fiber tracker · 2018. 11. 15. · LHCb SciFi Tracker, 12/03/2013 Detector feasibility studies • First studies focussed on:-radiation hardness