Maria Martinez (U. La Sapienza, Rome) on behalf of the CUPID-0 collaboration CUPID-0 A cryogenic calorimeter with particle identification for double beta decay search M. Martinez - U. La Sapienza (Rome) 1 WIN2017, June 19-24 (2017) WIN2017, Irvine, June 19 – 24, 2017.
Outline • CUORE: Bolometers for neutrinoless double beta decay • CUPID: Cuore Upgrade with Particle IDentification • CUPID-0: The first demonstrator • Summary 2 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Experimental search for 0𝜉𝛾𝛾 WHAT WE ARE LOOKING FOR EXPERIMENTAL SIGNATURE EXPERIMENTAL SENSITIVITY 𝐵, 𝑎 → 𝐵, 𝑎 + 2 + 2𝑓 − + 𝟑 𝟑𝛏𝛄𝛄: 𝝃 𝒇 Approach: Lifetime corresponding to the minimum • allowed in the SM and already SOURCE = DETECTOR detectable number of events over observed with T 1/2 > 10 18 y background at a given C.L.: n 𝟏𝛏𝛄𝛄: 𝐵, 𝑎 → 𝐵, 𝑎 + 2 + 2𝑓 − 𝑁𝑈 𝑇 0𝜉 ∝ 𝜗 𝑗. 𝑏. 𝑐 ≠ 0 𝑐Δ𝐹 𝑇 0𝜉 ∝ 𝜗 𝑗. 𝑏. 𝑁𝑈 n 𝑐 = 0 𝑵 : Total active mass in kg • not allowed in the SM 𝝑 : Detector efficiency • expected with T 1/2 > 10 25 y 𝒋. 𝒃. : Isotopic abundance If observed: 𝒄: Background in c/keV/kg/y • lepton number violation • neutrinos are Majorana particles 𝚬𝑭 : Detector resolution • measures effective electron @ ROI in keV neutrino mass 𝑼: Exposure time in y Main signature: Peak at Q- value over 2νββ tail enlarged only by detector resolution 3 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
CUORE: 1 ton TeO 2 bolometers See A. Branca’s talk LOOKING FOR 𝟏𝝃𝜸𝜸 of 130 Te 130 Te is part of the detector (i.a. ~ 34%) Data taking started on April 2017! 4 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Beyond CUORE: CUPID C UORE U PGRAGE WITH P ARTICLE ID ENTIFICATION CUPID goal: ∼ 0 bkg at ton scale CUPID Interest Group: 32 institutions • CUORE infrastructure • Isotope enrichment White papers: • Improved material arXiv:1504.03599 arXiv:1504.03612 selection • Particle identification To reduce background we need active 𝛽 discrimination 5 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Beyond CUORE: CUPID SENSITIVITY GOAL: CUPID STRATEGY Intense R&D exploring different technologies Explore the whole IH region 6 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Beyond CUORE: CUPID SENSITIVITY GOAL: CUPID STRATEGY Intense R&D exploring different technologies Explore the whole IH region 1 st PHASE CUPID-0 7 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Particle discrimination with scintillating bolometers A scintillating crystal at low Temperature + Another bolometer to detect the light The simultaneous readout of light & heat combines: • Good resolution of bolometers • Discrimination power of double readout detectors • Target choice 8 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
ZnSe Bolometers for 𝟏𝝃𝜸𝜸 The 𝛾𝛾 emitter: 82 Se The scintillating crystal: ZnSe • High Q-valu • High radiopurity lue ∼ 299 2998 keV eV decay: 9.6 × 10 19 years • Rather sl • Energy resolution 30 slow 𝟑𝝃𝜸𝜸 de 30 keV at t 3 3 MeV (1%) • Low natural isotopic abundance (8.7%) but • High light yield → excelle lent Successfully enriched to 96.3 96.3% dis discrimination po power I. Dafinei et al, arXiv:1702.05877 (2017) 9 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Alpha discrimination power • • Excellent discrimination based on the Excellent particle discrimination light/heat shape of the light pulse! • 𝛽 light yield > 𝛾/𝛿 → inverted behaviour respect to the usual one not well understood Eur. Phys. J. C (2016) 76:364 JINST 8 (2013) P05021 Q bb = 2995 keV 10 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
CUPID-0 • 24 Zn 82 Se bolometers (96% enrichment) + 2 ZnSe • Bolometers arranged in 5 towers. Every bolometer is surrounded by reflecting foil and faced to two Ge light detectors • Total mass: 10.5 kg ZnSe 5.17 kg 82 Se → 3.8 × 10 25 𝛾𝛾 emitters • • COMMISSIONED IN EARLY 2017 In operation @ LNGS (CUORE-0 cryostat) 11 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
High purity enriched Zn 82 82 Se Se • Se powder enriched at URENCO Stable Isotope Group (Netherlands) • Zn 82 Se synthesis and growth at ISMA (Ukraine) • Final enrichment: 96% Activities measured during a bolometric run: Eur. Phys. J. C76 (2016) 7, 364 arXiv:1702.05877 12 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Detector assembly 13 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Detector installation Detector installed in the former CUORE-0 cryostat with major upgrades: • Rn -abatement system next to the cryostat • Double stage pendulum for low vibrational noise • Improved cryostat wiring In March 2017 the commissioning was finalized and the data taking has started 14 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Detector performances Excellent light collection!! → High 𝛽/𝛾 discrimination power as expeced 2 Light detectors for every ZnSe Average FWH Energy resolution ∼ 25 keV The resolution is not limited by electronics (<5 keV), but dominated by the intrinsic crystal contribution → Room from improvement (for example, from light/heat correlation) 15 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Detector performances: Background in the 𝜸/𝜹 region Main background sources in the 𝛾/𝛿 region: • 65 Zn (cosmogenic activation of 64 Zn) ( 𝜐 1/2 =244 d) • 40 K & 232 Th in the experimental set-up (cryostat) • 𝟑𝝃𝜸𝜸 82 Se No puse-shape cuts (18 c/h, enriched crystals!) No 𝛾/𝛽 discrimination 16 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
First data 0.89 kg x y of exposure of ZnSe → 0.47 kg x y exposure of 82 Se Physics runs ongoing to increase statistics: • Compute and improve energy resolution • Prove that we can reach zer ero ba background in n the ROI First data will be released in summer 2017 No pulse-shape cuts No coincidence analyisis 17 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Summary ry • Completely exploring the inverted hierarchy region of neutrino masses will require a detector with ∼ 1 ton isotopic mass and background level at the order of 0.1 counts/ton/yr. • CUPID (Cuore Upgrade with Particle Identificiation) is pursuing this goal through several strategies, one of them being using scintillating bolometers. • ZnSe crystals and Ge-light detectors fulfill the project requirements both in terms of 𝛽 background rejection and energy resolution. • CUPID-0, the first CUPID demonstrator with Zn 82 Se is taking data at LNGS since March 2017. We expect to release the first data in Summer 2017 18 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
Thank you for your attention! 19 M. Martinez - U. La Sapienza (Rome) WIN2017, June 19-24 (2017)
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