FERMILAB-SLIDES-18-801-E Design and test of the Mu2e undoped CsI + SiPM crystal calorimeter Raffaella Donghia LNF-INFN and Roma Tre University On behalf of the Mu2e calorimeter group May 29, 2018 Frontier Detectors for Frontier Physics 14th Pisa Meeting on Advanced Detectors This document was prepared by Mu2e collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE- AC02-07CH11359.
Talk overview • Mu2e o CLFV Introduction o Experiment layout and detectors • Calorimeter requirements o Components o Single Channel Tests o Prototypes’ performance o Production phase Mu2e Calorimeter, R.Donghia May 29, 2018 1
Charged Lepton Flavor Violation • 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 a nucleus field Al e à discovery sensitivity to many NP models µ • Goal: 10 4 improvement w.r.t. current limit (SINDRUM II) μ -e conversion in the presence of a nucleus < 8.4 x 10 -17 Nuclear captures of muonic Al atoms More information (@ 90% CL, with ~ 10 18 stopped muons in 3 years of running) at mu2e.fnal.gov Mu2e Calorimeter, R.Donghia May 29, 2018 2
Mu2e experiment design 1. Generate low momentum μ - beam 2. Stop the muons in an Al target à trapped in orbit around the nucleus 3. Look for an excess around 105 MeV/c in the electron spectrum PS DS TS 25 m Production Solenoid / Target Detector Solenoid: stopping target and detectors • Protons hitting target and • Stops μ - on Al foils producing mostly π • Events reconstructed by detectors optimized for 105 MeV/c momentum Transport Solenoid • Selects and transports low momentum μ - Mu2e Calorimeter, R.Donghia May 29, 2018 3
Calorimeter requirements The electromagnetic calorimeter (EMC) should provide high acceptance for reconstructing energy, time and position of CEs for: 1) PID: e / μ separation 2) EMC seeded track finder 3) Standalone trigger Requirements @ 105 MeV/c • σ E /E = 𝓟 (10%) for CE • σ T < 500 ps for CE • σ X,Y ≤ 1 cm • Fast scintillation signals ( τ <40 ns) • Operate in 1 T and in vacuum at 10 -4 Torr • Redundancy in readout ( 2 sensors+FEE /crystal) • Radiation hardness (with a safety factor of 3): - 100 krad (45 krad) dose for crystals (sensors) - 3x10 12 n 1MeV /cm 2 (1.2x10 12 n 1MeV /cm 2 ) for crystals (sensors) • Low radiation induced readout noise < 0.6 MeV Front Disk Dose – 1 year [krad] Mu2e Calorimeter, R.Donghia May 29, 2018 4
Simulated performance ion LRU: RMS/MEAN of Light Output values along axis $ LYSO BaF 2 CsI • Simulation includes full background Radiation Length X 0 1.14 2.03 1.86 and digitization and cluster-finding, [cm] with split-off and pileup recovery 4 /36 Light Yield [% NaI(Tl)] 75 3.6 • The overall resolution depends on 0.9 /650 Decay Time[ns] 40 20 crystals features • Several crystals considered RMD APD SiPM Photosensor APD 220 /300 Wavelength [nm] 402 310 Mu2e Calorimeter, R.Donghia May 29, 2018 5
Calorimeter Design 2 annular disks with 674 undoped CsI (34 x 34 x 200) mm 3 square crystals/each disk R IN = 374 mm, R OUT = 660 mm o Depth = 10 X 0 (200 mm), Distance 70 cm o Redundant readout: o 2 UV-extended SiPMs/crystal 1 FEE / SiPM , Digital readout on crates o RA source for energy calibration o Laser system for monitoring o BETTER PICTURE!! Mu2e Calorimeter, R.Donghia May 29, 2018 6
Small prototype: Time and Energy resolution Small prototype 3x3 tested @ BTF (LNF) in 2015, 80-120 MeV e - 0.3 9 [ns] /E [%] Single crystal @ 0 deg Normal incidence JINST 12 (2017) P05007 data 8.5 h h All crystals above 10 MeV @ 0 deg t σ 0.25 Monte Carlo Entries Entries 0 0 E Cosmics 8 σ Mean 0 Mean 0 Neighboring crystals @ 50 deg 7.5 RMS 0 RMS 0 0.2 Single crystal @ 50 deg 7 Most energetic crystal @ 50 deg All crystals above 10 MeV @ 50 deg 0.15 6.5 6 0.1 2 2 / ndf / ndf χ χ 2.866 / 3 2.866 / 3 5.5 σ a E 2 2 / ndf / ndf χ χ 38 / 17 38 / 17 = b = a/E b ⊕ σ ⊕ a a 5 1.38 1.38 0.3253 0.3253 ± ± E t E [GeV] 0.05 a a 0.0049 0.0049 ± ± 0.00015 0.00015 4.5 b b 4.911 4.911 1.092 1.092 ± ± b b 0.087 0.087 0.0033 0.0033 ± ± 4 0 0.07 0.075 0.08 0.085 0.09 0.095 0.1 0.105 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 Total energy [GeV] Energy [GeV] σ E ~ 7 % at 100 MeV σ T ~ 110 ps at 100 MeV Significant leakage contribution due to block dimensions w.r.t. the shower 1 year long R&D phase for the final test of the option CsI + UV extended SiPM PRE-PRODUCTION 72 crystals + 150 SiPM + 150 FEE chips completed in 2016 Mu2e Calorimeter, R.Donghia May 29, 2018 7
Pre-production Crystals 24 crystals from SICCAS , Amcrys , Saint Gobain • Optical properties tested with 511 keV γ ’s along the crystal axis • 150 µ m Tyvek wrapping and UV-extended PMT readout • Longitudinal Resp. Uniformity Light Yield Un-doped CsI crystals Entries Entries RMS/MEAN of Light Entries 72 perform well: 12 10 Output values 10 along axis 8 • Excellent LRU and LY: 8 6 -100 pe/MeV 6 4 -LRU < 5% 4 2 2 τ of 30 ns (small slow § 0 0 0 1 2 3 4 5 6 7 8 9 10 100 110 120 130 140 150 160 170 180 190 200 component) Energy resolution N /MeV LRU (%) Q(200 ns)/Q(3000 ns) pe Entries Entries 14 16 SICCAS Fast/Total Radiation hardness OK 12 § Amcrys 14 10 LY loss < 40% (@ 100 krad) 12 Saint Gobain 10 8 8 6 6 4 4 2 2 0 0 60 65 70 75 80 85 90 95 100 105 10 11 12 13 14 15 16 17 18 19 20 F/T (%) σ / µ (%) Mu2e Calorimeter, R.Donghia May 29, 2018 8
Pre-production SiPMs Mu2e custom silicon photosensors: ~ 150 V à 2 arrays of 3 6 x 6 mm 2 UV-extended SiPMs: total area (12x18) mm 2 K1 The readout series configuration reduces the overall capacitance à faster signals 160 Amplitude [mV] Amplitude [mV] 500 6x6 mm 2 Series of Single cell of Entries 102900 Entries 102900 140 Entries 102900 Entries 102900 A1-1 Mean Mean 90.04 90.04 Mean Mean 90.09 90.09 120 400 3 cells 6 x 6 mm 2 Mean y 33.18 Mean y 33.18 Mean y 60.63 Mean y 60.63 100 RMS RMS 63.51 63.51 RMS RMS 63.51 63.51 300 RMS y RMS y RMS y RMS y 33.26 33.26 110.6 110.6 80 A1-2 60 200 40 100 20 A1 0 0 0 50 100 150 200 0 50 100 150 200 Time [ns] Time [ns] i1 ≈ i2 ≈ i3 C tot ≈ C1/3 150 sensors: 3×50 Mu2e pre-production SiPMs from Hamamatsu , SenSl and AdvanSiD • 3×35 were fully characterized for all six cells in the array Gain Neutron test I [mA] We need to 60 cool down Hamamatsu SiPMs at 0 ° 50 SenSl 40 AdvanSiD 30 20 10 9 10 0 0 100 200 300 400 500 600 700 800 2 Integrated flux [n /cm ] 1MeV Mu2e Calorimeter, R.Donghia May 29, 2018 9
Module 0 Large EMC prototype: 51 crystals, 102 SiPMs, 102 FEE boards Mechanics and cooling system similar to the final ones! Goals: • Integration and assembly procedures Test beam May 2017, 60-120 MeV e - • ( beam @ 0° and @ 50° ) t • Work under vacuum, low temperature, irradiation test wrapped F i n a l r e Readout: 1 GHz CAEN digitizers (DRS4 chip), 2 boards x 32 channels a d o u t d e i n t a C i a l s i u l o ’ s p Mu2e Calorimeter, R.Donghia May 29, 2018 10 o s t e r
Module 0 Energy resolution Perpendicular Beam 10 [%] 9 2 2 / ndf / ndf χ χ 1.132 / 1 1.132 / 1 dep a a 0.2 0.2 0.9182 0.9182 ± ± a 0.200 ± 0.092 /E 8 σ b b 0.3289 0.3289 ± ± 0.02063 0.02063 b 0.329 ± 0.021 7 c c 3.807 3.807 ± ± 0.3227 0.3227 c 3.807 ± 0.323 6 5 E beam = 100 MeV σ E ~ 5.4 % 4 a ⊕ b 3 σ E E ⊕ c √ Good agreement E = 2 E Data - MC 1 0 0.05 0.06 0.07 0.08 0.09 0.1 0.11 E [GeV] dep Beam @ 50° Preliminary 107887 136475 79070.2 127412 110208 97679.7 § Single particle selection Entries Entries 663136 663136 Mean x Mean x 0.01988 0.01988 Mean y Mean y 0.1337 − 0.1337 − Std Dev x Std Dev x 62.82 62.82 Std Dev y Std Dev y 55.23 55.23 0 0 0 0 0 0 0 0 0 0 0 0 122820 120963 67022.8 102991 98354.5 103408 76132.1 0 0 0 0 0 0 101734 104284 86969.5 128053 93017.6 103895 134562 106792 121208 122841 88138.3 135539 1.91335e+06 81310.4 108076 111132 79394.9 108205 100319 94299.6 112888 99920.4 123601 134589 104968 E beam = 100 MeV § Calibration − 98298.7 26479 130298 128720 151623 103162 104676 - MIPs − σ E ~ 7.3 % 107369 103181 87092.6 125962 106897 96822.4 - 100 MeV e - beam, up to ring 2 − − − − − − § Threshold applied after noise run @ 3 σ Mu2e Calorimeter, R.Donghia May 29, 2018 11
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