Design, status and perspective of the Mu2e crystal calorimeter Gianantonio Pezzullo INFN of Pisa on behalf of the Mu2e calorimeter group 1
Outline • The Mu2e experiment • Calorimeter design • The role of the calorimeter in Mu2e • R&D • Conclusion G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 2
The Mu2e collaboration ~200 scientists from 35 institutions Argonne National Laboratory, Boston University, Brookhaven National Laboratory University of California, Berkeley, University of California, Irvine, California Institute of Technology, City University of New York, Joint Institute for Nuclear Research, Dubna, Duke University, Fermi National Accelerator Laboratory, Laboratori Nazionali di Frascati, Helmholtz-Zentrum Dresden-Rossendorf, University of Houston, University of Illinois, INFN Genova, Kansas State University, Lawrence Berkeley National Laboratory, INFN Lecce and Università del Salento, Lewis University, University of Louisville, Laboratori Nazionali di Frascati and Università Marconi Roma, University of Minnesota, Muons Inc., Northern Illinois University, Northwestern University, Novosibirsk State University/Budker Institute of Nuclear Physics, Institute for Nuclear Research, Moscow, INFN Pisa, Purdue University, Rice University, University of South Alabama, Sun Yat Sen University, University of Virginia, University of Washington, Yale University G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 3
What is µ → e conversion • μ converts to an electron in the presence of a nucleus µ − N → e − N E e = m µ c 2 - B µ (Z) - C(A) = 104.973 MeV • for Aluminum: { B µ (Z) is the muon binding energy (0.48 MeV) C(A) is the nuclear recoil energy (0.21 MeV) • μ conversion in the SM is induced by neutrino masses and mixing at a negligible level ~ 10 -52 • Many SM extensions enhance the rate through mixing in the high energy sector of the theory (other particles in the loop…) ν N q q w w ν i µ - e - Supersymmetry Heavy neutrino ν MSM Lepto-quark Z’ exchange Effective contact : R ≤ 10 -13 exchange Muon conversion interaction : R ≈ 10 -52 G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 4
Historical perspective Hinks and Pontecorvo Limit @ 90% CL Lagarrigue and Peyrou TRIUMF SINDRUM II arXiv:1307:5787 Mu2e II • Mu2e will improve by a factor 10 4 the present best limit! G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 5
Experimental setup (1) Production Solenoid: (3) Detector Solenoid: ➡ Proton beam strikes target, producing ➡ Capture muons on Al target mostly pions ➡ Measure momentum in tracker and ➡ Graded magnetic field contains energy in calorimeter backwards pions/muons and reflects ➡ Graded field “reflects” downstream slow forward pions/muons conversion electrons emitted upstream 8 GeV protons (3) Al stopping (2) target (1) calorimeter tracker (2) Transport Solenoid: cosmic ray veto ➡ Select low momentum, negative muons ➡ Antiproton absorber in the mid-section G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 6
Calorimeter design • 2 disks; each disk contains 678 undoped CsI crystals 20 x 3.4 x 3.4 cm 3 • Disk separation ~ 75 cm • Inner/outer radii: 37.4/66 cm • Crystal choice: undoped CsI provides light yield (LY) > 100 pe/MeV, longitudinal response uniformity < 10%, emission decay time 𝛖 ~ 16 ns • Photosensor choice: custom array 2x3 of 6x6 mm 2 UV-extended SiPM undoped CsI SiPM array + FEE (R. Y. Zhu talk) (I. Sarra talk) G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 7
Calibration methods • Liquid source FC 770 + DT generator: 6 MeV + 2 escape peaks • Laser system to monitor SiPM performance 10k entries/crystal/min Liquid source prototype Laser system - test station G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 8
Radiation Environment • High level of dose impact on Si devices and crystals performance 13 3 10 10 Dose [krad/ year] /year] Total Total SiPM FLASH FLASH 2 SiPM dose DEUTERON 10 DEUTERON 12 2 10 OOT OOT 1 MeV-eq [# /cm neutron-damage PHOTON PHOTON NEUTRON NEUTRON PROTON 10 PROTON DIO DIO 11 10 1 10 10 1 − 10 n φ 9 10 2 − 10 3 8 − 10 10 400 450 500 550 600 650 400 450 500 550 600 650 R [mm] R [mm] 3 10 Dose [krad/ year] Total FLASH 2 DEUTERON 10 crystal dose OOT PHOTON NEUTRON 10 PROTON DIO 1 − 1 10 − 2 10 − 3 10 400 450 500 550 600 650 R [mm] G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 9
Simulation results • Offline simulation including background hits • Experimental effects included: longitudinal response uniformity (LRU), electronic noise, digitization, etc • Waveform-based analysis to improve pileup separation pile-up separation CE + background G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 10
PID: e/µ separation • 105 MeV/c e - are ultra-relativistic, while Entries / 0.01 6000 105 MeV/c µ have β ~ 0.7 and a kinetic CE µ @ 105 MeV/c 5000 energy of ~ 40 MeV 4000 • Likelihood rejection combines 3000 𝚬 t = t track - t cluster and E/p: 2000 1000 ln L e,µ = ln P e,µ ( ∆ t) + ln P e,µ (E/p) 0 0 0.2 0.4 0.6 0.8 1 1.2 E/p µ mimicking the CE Entries / 0.20 ns 12000 e e CE 2 2 / ndf / ndf χ χ 5569 / 90 5569 / 90 10000 µ @ 105 MeV/c Constant Constant 1.131e+04 1.131e+04 ± ± 4.222e+01 4.222e+01 Mean Mean − − 0.2208 0.2208 ± ± 0.0028 0.0028 Sigma Sigma 0.9264 0.9264 ± ± 0.0023 0.0023 8000 µ µ Al target χ χ 2 2 / ndf / ndf 322.2 / 57 322.2 / 57 6000 Constant Constant 2429 2429 14.5 14.5 ± ± Mean Mean − − 5.375 5.375 ± ± 0.010 0.010 4000 Sigma Sigma 1.671 1.671 ± ± 0.009 0.009 2000 tracker calorimeter 0 − 20 − 15 − 10 − 5 0 5 10 15 20 t [ns] ∆ G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 11
Calo seeded track finder • Cluster time and position are used for filtering the straw hits: ✓ time window of ~ 80 ns ✓ spatial correlation no selection calorimeter selection • black crosses = straw hits, red circle = calorimeter cluster, green line = CE track G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 12
Calorimeter trigger • Calo info can provide additional trigger capabilities in Mu2e: • Calorimeter seeded track finder : ✓ factorized into 3 steps: hit pre-selection, helix search and track fit ✓ ϵ ~95% for a background rejection of 200 • Standalone calorimeter trigger that uses only calo info: ✓ ϵ ~65% for a background rejection of 200 Bkg rejection ϵ ce Standalone Cali-Seeded calorimeter track finder ϵ ce Hit pre-selection helix search Kalman filter G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 13
Test with small prototype • Small prototype tested @ the BTF in Frascati during April 2015 • Array 3 x 3 with undoped CsI 3 x 3 x 20 cm 3 Calorimeter prototype coupled with Hamamatsu MPPC • All channels were read out with the 12 bit 250 Msps waveform digitizer board V1720 σ t [ns] 0.3 9 [ns] σ E /E [%] /E [%] Single crystal @ 0 deg data h h 8.5 All crystals above 10 MeV @ 0 deg t σ 0.25 Entries Entries 0 0 Monte Carlo 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] Energy [GeV] Energy [GeV] G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 14
New prototype • Large prototype: 51crystals + 102 SiPM + 102 FEE boards • Mechanics and cooling system similar to the final ones • Beam test successfully performed on 4-14 May 2017 @ BTF in Frascati using e - beam in the range [60, 120] MeV • Energy & timing resolution studied @ normal and 50 deg incidence • Analysis is underway BTF experimental hall G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 15
Conclusions • The Mu2e calorimeter has been designed to: ✓ operate in a very harsh environment (high ɣ and neutron dose) ✓ provide background rejection capabilities via PID ✓ make the track search more robust against background occupancy ✓ triggering capabilities • R&D steps well defined ✓ pre-production of crystals and SiPM already started ✓ QA processes of the main components already established ✓ large-scale prototype built and already under test using e - beam G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 16
backup slides 17
Muonic atom life times Ti G. Pezzullo (INFN of Pisa) TIPP’17 - May 22 2017 18
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