New Technologies for Dark Matter Searches XXX NATIONAL SEMINAR of NUCLEAR AND SUBNUCLEAR PHYSICS OTRANTO, 11 June 2018 Giuliana Fiorillo, Università di Napoli “Federico II”
Contents: lecture 3 • How to improve? Key technologies for LAr • ReD • DarkSide-Prototype • DarkSide-20k
From DarkSide-50 to DarkSide-20k 3
Why transition from PMTs to SiPMs? • Higher photo-detection efficiency • Better single photon resolution • Lower background • Lower cost • High dark rate • Small area → large number of preamps/cables/feedthroughs • High capacitance per unit area 4 4
What is a SiPM? • A SiPM is a matrix of SPADs and it usually has SPAD 1 × 1, 3 × 3, 6 × 6 mm 2 size • SPAD or μ cell (single photon avalanche photodiode) is the micro- component of a SiPM (10, 25, 35, 50, 100 mm) • Tile or Array is a matrix of SiPMs (up to 6 × 6 cm 2 ) � 5
Single Photon Avalanche Diode - SPAD SPAD (Geiger mode) Avalanche Photodiode Photodiode Gain = 10 4 -10 6 Gain = 10-1000 Gain = 1 V BR < V bias V APD < V bias < V BR V bias < V APD metastable Non linear response SiPM provide a pseudo- It’s a binary detector! like linear response by summing each SPAD jean-francois.pratte@usherbrooke.ca 6
Single Photon Avalanche Diode Operation Cycle 3: Recharge A C 1: Trigger 2 3 2: Quenching 1 B 1. Excellent single photon timing resolution 2. Sensitivity – single photon counting 3. Silicon � mass production � low cost 7 jean-francois.pratte@usherbrooke.ca
Specifically for Analog SiPM • Array of SPADs in parallel quenched passively by in-pixel resistor Hamamatsu jean-francois.pratte@usherbrooke.ca 8
� 9 C. Savarese EDU2017
� 10 C. Savarese EDU2017
Why transition from PMTs to SiPMs? • Higher photo-detection efficiency • Better single photon resolution • Lower background • Lower cost • High dark rate • Small area → large number of preamps/cables/feedthroughs • High capacitance per unit area Group the SiPMs and contend with G. Giovanetti 11 11
Requirements for DS-20k photodetector modules pulse shape discrimination pratical constraints • Detection efficiency > 40% • Operation at 87K • Timing resolution < O(10) ns • 5 × 5 cm 2 area per channel • Dark rate + noise trigger rate < • Power dissipation < 250 mW 0.1 Hz/mm 2 All requirements met and surpassed G. Giovanetti 12
� 13 G. Giovanetti
FBK NUV-HD low field • 10 x 10 mm 2 SiPMs • Peak efficiency in near UV • Low field reduces dark rate IEEE Trans. Electron Dev. 64 2, 2017
24 cm 2 single-channel detector
24 cm 2 single-channel detector • 24 FBK NUV-HD-LF SiPMs with optimized form factor and performance improvement • High density SPAD with high PDE • Peak sensitivity at ~ 420 nm • DCR ~ 5 mcps/mm 2 at 80 K • Higher over-voltage operation • The signal from the 4 x 6 cm 2 quadrants is summed with an active arXiv:1706:04220 adder ➡ Full 24 cm 2 tile with NUV-HD-LF at LN 2 5 V OV : • σ 1PE = 9% μ 1PE • SNR = 13 • 1PE Time resolution: 16ns • Total power dissipation ~ 170 mW • Dynamic range > 100 PE 16
24 cm 2 detector timing resolution single PE: σ = 16ns 17
ReD low energy calibrations and directionality in Liquid Argon
������������� ����������� ReD Experiment LAr-PSD LAr TPC Target Neutron Beam Scattering Angle ��������� Neutron N-PSD Neutron Detector N-TOF • ReD experiment has first beam in June @ LNS TANDEM • Original goal is the directionality measurement (high energy nuclear recoils), now aiming also at a direct measurement of low energy nuclear recoil with same TPC by tuning appropriately the beam and geometry setups • A significant reduction in Q y uncertainty and “some” indication of the underlying distribution of the number of ionization electrons at very low recoil would allow significant improvement in the sensitivity at lower masses (1-2 GeV/c 2 )
ReD TPC • Designed and built at UCLA • Optimized for neutron beam tests • Assembled at Naples CRYOLAB • In its dedicated LAr cryosystem B. Bottino and M. Caravati
Photoelectronics 2 5 × 5cm 2 tiles • 24 NUV-HD-LF rectangular SiPM, • 25 µm cell, 10 MOhm quenching resistor, • Arlon substrate • TOP • new 24 channels FEB • BOTTOM • 4 channels FEB
First signals Top tile Vbias= 28 V Ch A1 Bottom tile Vbias= 56 V Ch F2
S1&S2
DAQ
Commissioning @ Napoli Beam tests @LNS to calibrate with neutrons and sense directional sensitivity
DS-PROTO
1-ton prototype DS-20k RED TPC calibration purposes 27
A scalable design: Mother Boards � 28
Triangular Mother Board (TRB) 15 PDMs each Square Mother Board (SQB) 25 PDMs each
1ton prototype TPC
A physics-case for DS-Proto S2-only analysis background limited in DS50 Potential breakthrough: Total height 75 cm Active height 58 cm • Urania/Aria program • Use of SiPM • Larger mass in DS-Proto Bkg [0-50 Ne] composition PMT gamma 9% Cryo gamma Kr85 44% Ar39 Test bed for DS-20k technology to be installed at 40% CERN in 2019 370 SiPM tile photo-sensors Low background SS cryostat 8% Possible installation in LNGS in late 2019 Run in 2020?
39 Ar depletion in Urania+Aria • Urania plant is able to remove 85 Kr • By design more air leak tight wrt to DS50 plant → reduced 39 Ar content? • Relative volatility b/w 39 Ar and 40 Ar is 1.0015±0.0001 * • Thousands of distillation stages in a 350 m tall column (Seruci I) under construction in Nuraxi-Figus mine (Sulcis Iglesiente) • Would allow reduction of 39 Ar content by a factor 10 per pass • Seruci I production rate is calculated at 10 kg/day, perfectly matching the capacity needed to feed Ds-Proto (800 Kg total LAr) *from calculations
First modules at Seruci (20-3-2018)
SERUCI-0 @ Nuraxi Figus PIM 2017 - Cluj-Napoca 34 28 m
Low radioactivity photo-sensor • 5x5 cm SiPM tile with a front-end amplification & summing stage in an acrylic cage: a Photo Detector Module (PDM) • Intrinsically radio-pure Silicon • Screening of cryogenic electronic components and substrates to achieve the lowest possible radioactivity • Current estimate – including all services– is about 2 mBq/PDM, dominated by Arlon 55 NT substrates (for SiPM and front-end) • On-going fused silica substrates R&D can achieve factor 10 reduction (200 µ Bq/PDM) • To be noted, even 2 mBq/PDM much better than current DS50 PMT (compare to ~200 mBq/PMT)!
Future Darkside Low-Mass Searches 38 − 10 ] 2 [ cm 39 − 10 SI 40 − σ 10 i t on − 41 10 CL upper l i m 42 DS50 Expected Limit − 10 39 0.7 mBq/kg Ar, 2 mBq/PDM 39 0.07 mBq/kg Ar, 2 mBq/PDM 39 0.007 mBq/kg Ar, 0.2 mBq/PDM NEWS-G 2018 LUX 2017 − 43 10 XENON1T 2017 PICO-60 2017 PICASSO 2017 CDMSLite 2017 CRESST-III 2017 PandaX-II 2016 90% XENON100 2016 DAMIC 2016 44 − 10 CDEX 2016 CRESST-II 2015 SuperCDMS 2014 CDMSlite 2014 COGENT 2013 CDMS 2013 CRESST 2012 DAMA/LIBRA 2008 Neutrino Floor 45 − 10 1 10 2 M [GeV/c ] χ 1 year data taking with DS-Proto
DarkSide future program 20- 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 DS-Proto DS-20k GADMC DarkSide-20k GADMC detector a 20-tonnes fiducial argon a 300-tonnes depleted argon detector detector 100 tonne × year background-free 1,000 tonne × year background-free search for dark matter search for dark matter 37
A LAr shield for DarkSide-20k • AAr in ProtoDune style large cryostat to provide shielding and active VETO • allows to eliminate Liquid Scintillator Veto and Water tank ➡ Significantly simplify the overall system complexity and operation ➡ Fully scalable design for future larger size detector (300 ton) 38
CERN Neutrino Platform: • Two almost identical cryostats built for NP02 and NP04 experiments • About 8x8x8 m 3 inner volume, 750 t of LAr in each one • Cryostat technology and expertise taken from LNG industry • Construction time: 55 weeks (NP04), 37 weeks (NP02) • Thought since the beginning to be installable underground
DarkSide-20k nVeto conceptual design • TPC thin copper vessel to be surrounded by an active plastic scintillator layer as a neutron veto • Considering options to load with Boron or Gadolinium for increased capture cross section • Cryogenic SiPM sensors in Liquid sensors similar to those developed for the TPC • Detector concept minimize internal neutron background sources and allow easier scaling for bigger target mass
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