1. Francesca Cavallari (INFN Roma)
ECAL upgrade per Roma
Francesca Cavallari (INFN Roma)

2. Indice
ECAL longevity studies
New ideas
Plans of the Upgrade Group

3. Radiation damage on crystals
Gamma irradiation creates color centers which reduce the crystal transparency up to a saturation level, which depends on the dose rate. The damage is spontaneously recovered at room temperature.
Hadron damage creates clusters of defects which cause light transmission loss. The damage is permanent and cumulative at room temperature

4. ECAL monitoring response in 2011-2012EB
EE (eta=2.6)
L (cm-2 s-1)
Lint (fb-1)
gamma dose rate (Gy/h)
Protons
/cm2
design
1x10^34
500
0.3
4x10^11
6.5
3x10^13
2012
6x10^33 23
0.2
1.8x10^10 4
1.4x10^12
HL-LHC
1x10^35
3000 3
2.4x10^12 65
2x10^14

5. Transmission loss due to hadrons
We define the μIND
Due to the transparency loss induced by irradiation,  there is a decrease of light collected
50 GeV e- LO

6. Prediction of μIND from S. Ledovskoy model [see p.26]
Righe disegnate da me,
da non diffondere
from S. Ledovskoy model [see p.26]

7. Expectations for ECAL signal losses
A reduction of Light Output induces:
a reduction of photostatistics
a loss of uniformity in light collection
an increase of noise over signal ratio
The corresponding terms in the energy resolution are affected
Additionally: VPT aging
CMS ECAL
Fraction of ECAL response - F
Simulation
50 GeV e-
November 1st, 2012
Francesca Nessi-Tedaldi (CMS) paper N35-4

8. Effect of crystal transparency deterioration on the energy resolution
Resolution for the calorimeter is given by 3 terms:
𝜎(𝐸) 𝐸 = 𝑎 𝐸 ⨁ 𝑏 𝐸 ⨁𝑐
𝑎 𝑝ℎ𝑜𝑡 = 𝐹 𝐿𝑌
b∼ 𝑁𝑜𝑖𝑠𝑒 (𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛𝑠) 𝐿𝑌 ( 𝑝𝑒 𝑀𝑒𝑉 )
𝑐∼ 1 𝐿𝑌 𝜕𝐿𝑌 𝜕𝑧 𝛿𝑧
The radiation damage affects the 3 terms in this way:
a: deterioration of the stochastic term
b: amplification of the noise equivalent in MeV
c: deterioration of the light collection uniformity
(F =APD excess noise factor ~ 2)

9. Effect of the transparency loss on light collection uniformity

10. 1) Deterioration of energy resolution due to light collection non-uniformity
Npe
MeV
Crystal uniformity at construction ~0.3%/X0
|dLY/X0 | < 0.35%/X0 between 3 and 13 X0
FNUF = Front Non-Uniformity, slope of the Light collection curve in the front between 3 and 13 cm

11. 1) Deterioration of energy resolution due to light collection non-uniformity
TEST-BEAM measurements of heavily p-irradiated crystals. CMS Note in preparation

12. 1) Deterioration of energy resolution due to light collection non-uniformity
Model prediction for the constant term increase due to the non uniformity of the light collection

13. 2) Non-linearity due to light collection non-uniformity
The longitudinal profile of the energy deposit of high energy e.m. showers depends on energy
If the light collection is not uniform this generates a non-linearity of energy response

14. 2) Non-linearity due to light collection non-uniformity
TEST-BEAM measurements of heavily p-irradiated crystals

15. More on p-irradiations
The proton irradiations were done with beam lines and in a very short time (may affect the uniformity of proton exposure and the recovery dynamics)
4 crystals were placed in CMS cavern on the CASTOR table for few months during 2012 data-taking, to study slow and more uniform proton irradiations. The crystals were just removed and will be measured soon.

16. Crystal transmission damage: thermal+optical recovery

17. EE VPT response loss VPT AGING DUE TO ACCUMULATED CHARGE
Burn-in tests in UVA and Brunel are summarized by D. Cockerill at ECAL Monitoring and Calibration Meeting, June 14, 2012
The model assumes an exponential degradation up to a plateau at 77%.

18. Noise evolution

19. Noise evolution in ECAL in 2011-2012

20. ECAL Barrel APD radiation damage
APDs are silicon devices and are sensitive to neutron damage
APD neutron radiation damage causes increase in dark current proportional to the neutron fluence
Each HV channel gives bias to 50 capsules (100 APDs).

21. ECAL Barrel APD radiation damage
(Calculations refer to damage at 18C and 2 days after irradiation.
The permanent damage is about 50% of this)
[MARS] simulation by Pushpa Bhat and collaborators
see
TRK/PIX-oriented study, not sure that calorimeters volumes are perfectly described
(not sure about neutron moderator)
NIEL calculations simply add charged and neutrals, no energy weighted damage.
Need more manpower to improve the study/validate and for the 7-8TeV to 14TeV ratio
ECAL is part-funding a technical student to work on FLUKA simulations

22. ECAL Barrel APD radiation damage
One short term component that recovers in 20 days
One long term (permanent?) component that carries about 50% of the damage.
The observed η profile is in agreement with MARS and TDR radiation damage expectations (damage at end of EB ~ 2 x damage at η=0)

23. Noise increase (noise of the single sample)
ECAL has a sampling ADC and we read 10 samples
This is the noise of the single sample
measurements
Special scan
at high APD gain
The fit function is: noise= 𝑛𝑜𝑖𝑠𝑒(0) 2 +𝑚 𝐼𝑑𝑎𝑟𝑘
noise(0)=40.99 MeV m=830+/-100 MeV2/μA

24. From noise of the single sample to noise on the pulse amplitude (=rechit)
The pulse amplitude is calculated with the weight method:
Amplitude= Σ wi Ai (i=1,...,10)
We use pedestal-subtracting weights and the Noise on the amplitude of the single crystal is given by
Noise(Amplitude)=
= Σ wi2 x noise(single sample)
= 0.9 x noise(single sample)
Instead if the pedestals are subtracted from standalone pedestal run =>
Noise(Amplitude)=0.6 x noise(single sample)
Effect of pile-up to be studied with simulations

25. Leakage current in ECAL preshower sensors
Good agreement with FLUKA+Hamburg model , factor of 2 more neutrons with respect to TDR

26. New ideas
Shashlik calorimeter with LYSO or YSO or CeF3 and Lead or Tungsten
Absorber + crystal fibers

27. Shashlik with crystals

29. Crystal Fiber Calorimeter
LUAG fibers (+ Ce doping)
7000 ph/MeV

30. ECAL Barrel electronics
The spikes become very noisy at high luminosity
It is not clear how the trigger will cope
So the idea is to use the tracker in the trigger (the tracker has to be redone anyway, so it will have faster electronics that can serve in the trigger too)
Hence the need for higher latency
Hence the need to rebuild the ECAL FE electronics
Not clear how the photons will do ...

31. Upgrades ESP
ECAL Longevity studies and documentation [ longevity studies and possibly bleaching, annealing studies, ES studies + writing the longevity report]
Simulation software development for phase II [ fast - full sim - and geometry sw development ]
Validation of CMSSW releases for the upgrade part [ the person who validates the releases for the ECAL upgrade part, the releases which are specially for the upgrades, the upgrade specific conditions, the aging part, the reco in high pile up]
Studies of performance on physics objects and benchmark channels for phase II [ studies of performance of electrons and photons in the phase II conditions and with aged detector (energy resolution and linearity, calibration)+ studies of performance on physics channels in the phase II conditions and with aged detector for what concerns the ECAL]
Reconstruction studies and reconstruction software development for phase II [studies of pulse amplitude reconstruction in higher noise environment and high pile-up, studies of clustering in high pile-up, studies of timing and vertex localisation from ECAL in phase II conditions ]

32. Upgrades ESP
Trigger studies and spike killing studies for phase II [ECAL trigger studies including spikes - trigger electronics studies for phase II ]
Contact with Trigger group for upgrades [a person who follows the trigger TDR and the trigger group for phase II]
Electronics studies and development for phase II [study of detector occupancy, selective readout algorithms and the need or not for electronics upgrade for phase II and if that is the case starting to develop the new electronics]
Radiation and activation calculation [studies with FLUKA to calculate the gamma dose and hadron fluency calculation in the detector and comparison with the existing data from the detector - activation calculation ]

33. Muons High Eta Tracker Physics Reps: POG Reps: Detector Reps:
Upgrade Project Office
Spalding+ Contardo
Forward Detector Upgrade WG
Mannelli + Rusack
Technical Advisory Group
Calorimeter
Cox + Ruchti
Software Tools and Simulations
Chlebana + Bornheim
Pile-up Suppression
LeCoq+ TBD
Integration and Planning
Funk + TBD
Muons
Benvenuti + Safanov
High Eta Tracker
Abbaneo + Venturi
Physics Reps:
Higgs - Giacomelli + Klute
EXO – Brooke + Dahmes
SUSY - Melzer-Pellmann Hatakeyama
Heavy Ions – Murray
POG Reps:
E/Gamma
Jets & MET TBD
B-tag
Top
Muons
Detector Reps:
HCAL - Moisenz/Yetkin
ECAL – Cavallari + Jessop
Trigger – Jeitler
FSQ - Cartiglia