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

Indice ECAL longevity studies New ideas Plans of the Upgrade Group

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

ECAL monitoring response in 2011-2012 EB 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

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

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

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

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)

Effect of the transparency loss on light collection uniformity

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

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

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

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

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

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.

Crystal transmission damage: thermal+optical recovery

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%.

Noise evolution

Noise evolution in ECAL in 2011-2012

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).

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 http://cmstrk.fnal.gov/radsim/LHC_DoseFlux_Calculator.html 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

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)

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 2011-12 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

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

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

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

Shashlik with crystals

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

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 ...

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 ]

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 ]

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