FERMILAB-SLIDES-18-79E The Mu2e crystal calorimeter Eleonora Diociaiuti LNF-INFN and Tor Vergata University on behalf of the Mu2e calorimeter group 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. July 7, 2018 XXXIX INTERNATIONAL CONFERENCE ON HIGH ENERGY PHYSICS
Talk overview • The Mu2e experiment - CLFV introduction - Experiment layout • Mu2e Electromagnetic Calorimeter - Components - Performance - Production status E. Diociaiuti | LNF-INFN 2 07/07/2018
Charged Lepton Flavor Violation M o r e i n • CLFV processes are forbidden in SM f o i n G . P e z z u l l o Even allowing neutrino oscillation BR ~ 10 -54 t a l k - • Observation of a CLFV process: clear evidence of New Physics • Mu2e : Coherent muon conversion in the electric field of a nucleus Broad sensitivity across different models - E e = m µ c 2 − ( B.E. ) 1 S − E recoil = 104 . 96 MeV Very clear signature: monoenergetic electron - µ-e conversion in the field of a nucleus µ − + N ( A, Z ) → e − + N ( A, Z ) µ − + N ( A, Z ) → ν µ + N ( A, Z − 1) < 8 . 4 × 10 − 17 8 × 10 − 17 R µe = Nuclear capture of muonic Al atom • Improve of 4 orders of magnitude the previous limit set by the SINDRUM II experiment (6.1× 10 -13 ) E. Diociaiuti | LNF-INFN 3 07/07/2018
The Mu2e experiment PRODUCTION SOLENOID Protons hitting the target and producing mostly π • Graded magnetic field reflects slow forward π • TRANSPORT SOLENOID π decay to µ • Selection and transportation of low momentum µ - • 25 m DETECTOR SOLENOID Capture µ on the Al target • Momentum measurement in the tracker and energy reconstruction with calorimeter • CRV to veto cosmic ray events • E. Diociaiuti | LNF-INFN 4 07/07/2018
Calorimeter requiremens High acceptance for reconstructing energy, time and position of signals for : - Particle Identification: e/µ separation à reject µ background Improve the track pattern recognition - Standalone trigger - @ 105 MeV Crystals coupled with Silicon Calorimeter requirements PhotoMultipliers(SiPM) Light Yield(photosensor)>20 pe/MeV • • energy resolution σ E /E <10% Fast signal for pileup and timing • • timing resolution σ(t) < 500 ps Survive an high radiation • • position resolution < 1 cm environment • Work in vacuum @ 10 -4 Torr − Total Ionizing Dose (TID) of 90 krad/5 year for crystal • 1 T Magnetic Field − TID of 75 krad/5 year for sensor − 3x10 12 n/cm 2 for crystal − 1.2x10 12 n/cm 2 for sensor E. Diociaiuti | LNF-INFN 5 07/07/2018
Calorimeter Design 2 disks each with 674 undoped (34x34x200)mm 3 square pure CsI crystals Readout: 2 UV-extended SiPMs/crystal • Analog FEE and digital electronics located • in near-by electronics crates Source for energy calibration • Laser system for monitoring gain stability • E. Diociaiuti | LNF-INFN 6 07/07/2018
Mu2e EMC: MC performance The calorimeter energy resolution is estimated taking into account signal and predominant background, as the difference of the conversion electron energy and the cluster energy. FWHM/2,35 = 3.8 ± 0.1 MeV The overall resolution depends on the crystal features Longitudinal Response Uniformity LRU=RMS/MEAN of LO along the crystal E. Diociaiuti | LNF-INFN 7 07/07/2018
Crystal preproduction • 24 crystals from three different vendors: SICCAS , Amcrys , Saint Gobain 22 Na source to test crystal properties along the crystal axis • • Crystals coupled in air to an UV-extended PMT Optical properties: • 100 pe/MeV with PMT − readout − LRU < 5% − Fast/Total>75% Radiation hardness • − Smaller than 40% LY loss @ 100 krad − Radiation Induced Noise <0.6 MeV Selected vendors: SICCAS and Saint Gobain E. Diociaiuti | LNF-INFN 8 07/07/2018
SiPM preproduction • 2 arrays of three 6x6 mm 2 SiPMs ~ 150 V total active area of (12x18) mm 2 - 50 µm pitch - 6x6 mm 2 • Photon Detection Efficiency (@ 315 nm)>20% • The series configuration à narrower signals 150 Pre-production SiPMs (3 × 50 Mu2e SiPMs • from Hamamatsu , SensL and AdvanSiD ): 3 × 35x6 cells fully characterized (V op , G, I dark , PDE) - 1 sample/vendor exposed up to a fluence of - 8.5 × 10 11 n 1MeVeq /cm 2 (@ 20 ° C) Selected vendor: Mean Time To Failure estimated by operating 15 Hamamatsu - SiPM at 50 °C for 3.5 months à MTTF > 0.6x10 6 h I [mA] Hamamatsu • 60 SensL • AdvanSiD 50 • 40 30 20 10 9 10 0 0 100 200 300 400 500 600 700 800 2 Integrated flux [n /cm ] 1MeV E. Diociaiuti | LNF-INFN 9 07/07/2018
Module-0 Large size prototype: 51 crystals coupled to 102 sensors t Goals: • wrapped Test the performances - Test integration and assembly - procedures e - beam (60-120 MeV), May 2017 - Orthogonal and 50° incidence • (CE) Operate under vacuum, low - temperature and irradiation tests • Readout: 1 GHz CAEN digitizers (DRS4 chip), 2 boards x 32 channels E. Diociaiuti | LNF-INFN 10 07/07/2018
Module-0: Energy resolution Orthogonal incidence • Single particle selection Entries/1 MeV Entries Entries 1902 1902 160 Mean Mean 87.87 87.87 • Calibration: Std Dev Std Dev 7.702 7.702 140 2 2 χ χ / ndf / ndf 23.5 / 12 23.5 / 12 Cosmic - η η 0.2011 0.2011 ± ± 0.0846 0.0846 120 σ σ 4.723 4.723 ± ± 0.199 0.199 Beam - 100 µ µ 89.48 89.48 ± ± 0.29 0.29 1552 1552 50.2 50.2 N N ± ± 80 Orthogonal Run: 60 DATA σ E ~ 5% MC 40 Tilted Run : 20 σ E ~ 7.5% 0 0 20 40 60 80 100 120 @ E beam = 100 MeV E [MeV] 50° incidence 10 90 Entries/ 1 MeV [%] Orthogonal Beam Entries Entries 1190 1190 9 80 dep 2 2 χ χ / ndf / ndf 26.39 / 27 26.39 / 27 Beam @ 50 ° /E 8 70 σ η η 0.07021 0.07021 0.04812 0.04812 ± ± 7 60 σ σ 6.572 6.572 ± ± 0.202 0.202 6 µ µ 88.12 88.12 ± ± 0.38 0.38 50 a ⊕ b σ E 5 1108 1108 33.8 33.8 N N ± ± E ⊕ c √ E = 40 E 4 30 2 2 DATA χ χ / ndf / ndf 0.8783 / 2 0.8783 / 2 χ χ 2 2 / ndf / ndf 3.142 / 3 3.142 / 3 3 a a 0.6 0.6 ± ± 0 0 a a 0.6 0.6 0 0 ± ± MC 20 2 b b 0.2732 0.2732 0.02913 0.02913 ± ± b b 0.3747 0.3747 ± ± 0.045 0.045 c c 4.05 4.05 0.2705 0.2705 ± ± c c 5.863 5.863 0.3911 0.3911 ± ± 10 1 0 0 0 20 40 60 80 100 120 0.05 0.06 0.07 0.08 0.09 0.1 0.11 E [GeV] E [MeV] dep E. Diociaiuti | LNF-INFN 11 07/07/2018
Module-0: Single Sensor Time resolution Amplitude [mV] 350 • Log Normal fit on leading edge TimeHist TimeHist 300 2 2 Χ / ndf / ndf 106.6 / 20 106.6 / 20 Constant Fraction method used CF = 5% 250 η 0.6526 0.6526 0.0444 0.0444 • σ 17.12 17.12 1.21 1.21 200 • Comparison between 1GHz (TB sampling) and 216.6 216.6 0.7 0.7 μ 150 200 MHz (Mu2e sampling) shows no deterioration N N 8782 8782 640.2 640.2 100 in the resolution 50 0 Entries / (0.075 ns) 250 0 200 400 600 800 1000 Entries Entries 1531 1531 t [ns] Central Crystal 2 2 / ndf / ndf 19.56 / 15 19.56 / 15 200 σ (T1+T2)/ ! ~ 132 ps Constant Constant 240.9 240.9 7.6 7.6 150 @ E beam = 100 MeV Mean Mean 0.1664 0.1664 0.0049 0.0049 100 Sigma Sigma 0.1874 0.1874 0.0035 0.0035 50 0.5 [ns] o 0.45 Beam at 0 - Hamamatsu 0 T 1.5 1 0.5 0 0.5 1 1.5 σ Cosmic Rays - Hamamatsu t [ns] Δ 0.4 o Beam at 50 - SensL 0.35 Cosmic Rays - SensL Central Crystal 0.3 σ t = a 0.25 E ⊕ b 0.2 0.15 0.1 2 2 / ndf / ndf 2 2 / ndf / ndf χ χ 3.081 / 5 3.081 / 5 χ χ 5.155 / 3 5.155 / 3 a a a a 8.906 8.906 ± ± 0.2043 0.2043 6.858 6.858 ± ± 0.1425 0.1425 0.05 b b 0.118 0.118 ± ± 0.007005 0.007005 b b 0.0911 0.0911 ± ± 0.004349 0.004349 0 10 20 30 40 50 60 70 80 90 100 Energy [MeV] E. Diociaiuti | LNF-INFN 12 07/07/2018
QA room @ FNAL for production • QA tests started on March 2018 ~1000 SiPMs tested (25% of the total number) - ~300 crystals (23% of the total number) - CsI dimensional test CsI RIN CsI QA Motor support Motor on the back moves source + tagger 6 crystals tested at the same time + tagger CS 137 holder Na 22 behind a Lead shielding + tagger UV PMT 2 SiPMs per crystal Diffusing sphere Motor for (Gain measurement) Tyvek cap CsI holder TranslaKon motor RotaKng motor (CsI & sphere) (to test a and b sides) LED SiPM Power driver SIPM dimensional test SiPM QA SiPM MTTF E. Diociaiuti | LNF-INFN 13 07/07/2018
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