Design and status of the Mu2e crystal calorimeter Raffaella Donghia National Laboratory of Frascati of INFN On behalf of the Mu2e calorimeter group June 11, 2019 New Perspectives 2019 Fermi National Accelerator Laboratory
CLFV @ Mu2e CLFV strongly suppressed in SM: Branching Ratio ≤ 10 -54 E CE = m µ c 2 – E b – E recoil = • à Observation would indicate New Physics = 104.97 MeV CLFV @ Mu2e: μ - e conversion in the field of a nucleus • e Al à discovery sensitivity to many NP models µ n o t i < 8.4 x 10 -17 a m r o f n i e r o M k l a t g n u j i Y n i PS DS TS 25 m Production Solenoid / Target Detector Sol De olenoi oid: stopping target & detector ors Protons hitting target and producing • Stops μ - on Al foils • mostly π Events reconstructed by detectors optimized • Transport Solenoid Tr for 105 MeV/c momentum Selects and transports low • momentum μ - NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 1
Calorimeter requirements The electromagnetic calorimeter (EMC) should provide high acceptance for reconstructing energy, time and position of conversion electrons (CE) and provide: 1) 1) PID: e / μ se PI separa rati tion 2) 2) EMC EMC seeded track fi finder 3) 3) Fa Fast and nd track-in independent trig igger Requirements @ 105 MeV/c σ E /E = 𝓟 (10%) for CE • σ T < 500 ps for CE • σ X,Y ≤ 1 cm • Fast signals, τ <40 ns • Operate in 1 T and in vacuum at 10 -4 Torr • Redundancy in readou Re out ( 2 se senso sors+ rs+FEE /c /crystal) • Radiation Ra on hardness (safe fety fa factor or of of 3): • - 100 100 kr krad (4 (45 kr krad) ) dose for crystals (s (sensors) 12 n 1M - 3x 3x10 10 12 12 n 1M eV /c /cm 2 2 (1 (1.2x10 12 eV /c /cm 2 ) ) for crystals (s (sensors) ) 1MeV 1MeV Low radiation induced readout noise < 0.6 MeV Front Disk Dose – 1 year [krad] • NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 2
Calorimeter Design Tw Two annular disks with 674 und undoped ed Cs CsI (3 (34 x x 34 x x 200) ) mm 3 3 sq square cryst stals s each R IN = 374 mm, R OUT = 660 mm o Depth = 10 X 0 (200 mm); Distance = 70 cm o ~ 150 V Redundant readout: o K1 2 2 UV-ex extended ended Si SiPMs/c /crystal (Mu2e Si SiPMs) 6x6 mm 2 18 mm 2 ac à 50 50 um um pi pixel el, 12x 12x18 active ar area 1 FEE / SiPM, digital readout on crates o Lo Long R&D phase to select final producer o A1 i 1 ≈ i 2 ≈ i 3 C tot ≈ C/3 BETTER PICTURE!! NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 3
Module 0 Large EMC prototype: 51 crystals, 102 SiPMs, 102 FEE boards Mechanics and cooling system similar to the final ones but smaller scale à Main goals: • Integration and assembly procedures Test beam May 2017, 60-120 MeV e - ( @ 0 ° and @ 50 ° ) • • Work under vacuum, low temperature, irradiation test t wrapped Readout: 1 GHz CAEN digitizers (DRS4 chip), 2 boards x 32 channels NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 4
Module 0 TB results Beam @ 50 ° Energy response - Single particle selection - MIPs Equalization & E-scale a ⊕ b σ E E ⊕ c √ E = E - LY/SiPM = 30 pe/MeV Δ - Great Data-MC agreement σ E ~ 7.3 % 0.35 Time response [ns] Time response o Beam at 0 - Log-normal fit on leading edge T 0.3 σ Cosmic Rays - Hamamatsu o - Constant Fraction method used à CF = 5% Beam at 50 0.25 Cosmic Rays - SensL σ T = a/E + b Entries / (0.075 ns) 0.2 Amplitude [mV] 350 250 TimeHist TimeHist Central crystal Entries Entries 1531 1531 Χ (T SiPM 1 – T SiPM2 ) 300 2 2 / ndf / ndf 106.6 / 20 106.6 / 20 2 2 200 / ndf / ndf 19.56 / 15 19.56 / 15 0.15 η 250 0.6526 0.6526 0.0444 0.0444 Constant Constant 240.9 240.9 7.6 7.6 σ 17.12 17.12 1.21 1.21 200 150 0.1 Mean Mean 0.1664 0.1664 0.0049 0.0049 216.6 216.6 0.7 0.7 150 µ 100 N N 8782 8782 640.2 640.2 Sigma Sigma 0.1874 0.1874 0.0035 0.0035 2 2 100 2 2 / ndf / ndf / ndf / ndf χ χ 1.631 / 5 1.631 / 5 χ χ 2.776 / 3 2.776 / 3 0.05 a a a a 50 6.29 6.29 0.2011 0.2011 4.85 4.85 ± ± 0.1399 0.1399 ± ± 50 b b 0.08285 0.08285 0.006919 0.006919 b b 0.06402 0.06402 ± ± 0.004284 0.004284 ± ± 0 0 0 0 200 400 600 800 1000 Δ 1.5 1 0.5 0 0.5 1 1.5 Δ 10 20 30 40 50 60 70 80 90 100 t [ns] t [ns] Highest Energy Crystal [MeV] Energy [MeV] NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 5
QA of components for production (2018-2019) Dedicated QA laboratory at SiDet (FNAL) è production started on March 2018 Additional laboratories for crystals and irradiation testing at Caltech and HZDR Crystals Light Yield More than 1000 crystals already tested from SICCAS (rate: 60 crystals/month), SG almost same rate Optical properties measurements: • LY, LRU, resolution, slow component, RIN More details on E.Diociaiuti poster SiPMs RMS RMS (V br ) (I dark ) About 3200/4000 Mu2e SiPMs already characterized Producer: HAMAMATSU 280 pieces/month • All 6 cells tested, measuring V br , I dark , Gain x PDE • Irradiation with ~1x10 12 neutrons/cm 2 (MTTF) test • on 5 (15) SiPMs/batch NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 6
FEE & Digital readout De Dedica cated FEE board on each ch Si SiPM PM: : 2 amplification stages (x 2, x4) • Linear regulation of bias voltage • Shaping: • à Rise time 50 ns à Full width 200 ns 1 V dynamic range • Monitoring of SiPM currents/temperature • rad-hard up to 100 krad • 10 10 crates es per er disk with h 6-8 8 digital boards/crate MB DIRAC 20 SiPM+FEE channels per board • Mezzanine (M (MB) : input FEE signals, HV to SiPMs • DI DIRAC board provides digitization at 200 Msps, 12 bit ADC • DC-DC converter • VTRX optical readout • Final Rad-Hard FPGA PF300T à Rad-hard up to 15 15 kr krad • NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 7
Final Mechanical design Crystals stacked from the bottom to the top inside an external stainless steel cylindrical support FEA completed: good stability, small stress on support legs • Inner cylinder: composite material • FEE plate: PEEK • CF front face with source tubing integrated • FEE crates mounted on the external cylinder • mockup with fake iron crystals Geant4 simulation 2 calibration systems integrated: radioactive source and laser system • NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 8
Additional IN-SITU calibrations Cosmic Rays dE/dX à equalize and calibrate the energy response; • Time of flight à to align the time offsets • Energy scale at O( 1%) • Estimated time 6 hours • Continuous monitor E-T resolution • calibrate T 0 s @ a level below 30 ps (RMS) • DIO electrons Calibration relative to tracker measurements High energy tracks from DIO electrons • Absolute calibration at 0.5 T • Calibration extrapolation to 1 T, accuracy ~ 0.2% • NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 9
Calorimeter Assembly room Assembly Room under construction at FNAL in SiDet • Completion scheduled for March 2019 o Stacking procedure of wrapped crystals OK New Photo Getting ready to start assembly in November 2019! NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 10
Summary and Conclusions • The Mu2e calorimeter concluded its prototyping phase satisfying the Mu2e requirements: • Un-doped CsI crystals perform well § Excellent LRU and LY > 100 pe/MeV ( PMT+Tyvek wrapping ) τ of 30 ns, negligible slow component § § Radiation hardness OK : 40% LY loss at 100 krad • Mu2e SiPMs quality OK • High gain, high PDE, low I dark , low RMS spread in array • SiPMs performance after irradiation OK à require 0 ° C cooling • Calorimeter prototypes tested with e - beam § Good time and energy resolution achieved @ 100 MeV • Calorimeter production phase started March 2018 • Production will end in October 2019, FEE production on summer 2019 • Calorimeter assembly expected by the end of 2019 • Calorimeter installation in Mu2e experimental hall planned for 2020 NP19 - Mu2e Calorimeter, R.Donghia June 11, 2019 11
Thanks for listening Raffaella Donghia On behalf of the Mu2e calorimeter group June 11, 2019 New Perspectives 2019 Fermi National Accelerator Laboratory
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