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An Array of Bolometers for Rare Event’s Search

An Array of Bolometers for Rare Event’s Search. Peng Haiping ,Xuzizong State Key Lab. of Particle Detection and Electronics(USTC) Collab . Innova . Center for Particles and Interactions. 1 Introduction 2 Bolometers for Rare Event Search 3 Outlooks. 1. Introduction.

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An Array of Bolometers for Rare Event’s Search

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  1. An Array of Bolometers for Rare Event’s Search Peng Haiping ,Xuzizong State Key Lab. of Particle Detection and Electronics(USTC) Collab. Innova. Center for Particles and Interactions

  2. 1 Introduction 2 Bolometers for Rare Event Search 3 Outlooks

  3. 1. Introduction • Interactions of Particles with Medium of Detector • Heat(phonons) is really responding to energy deposit of particles in the detector • Bolometer is most powerfull detectors with high energy resolution and low energy threshold in energy measurement • 2D-output’s Bolometer of high capability to identify NR from ER events

  4. Introduction1 §1.1 Interactions of Particles with Medium of Detector Elastic collisions : NR-Nuclear Recoils or ER- electron recoils Energy deposit in detector ER Mean phonon enengy: ɛp =2.7kBT =0.23meVK-1 In the Debye approximation Inelastic collision : a small amount of deposit energy for ionization Ar:26eV/ion pair Semicon.Si: 3.6eV/e-h pair ,30% Ed for e-h pair and 70% Ed for phonons Scinti.Crystal: a small amount of deposit energy Ed for fluor. Photons: 40000/MeVx3eV=0.12~12% for photons and 88% for phonons

  5. Introduction2 Bolometer - the detectors are based on phonon or quasi-particle’s measurement Semiconductor -D - the detectors are based on eletcron–hole pair’s measurement Gas detetor - the detectors are based on electron - ion pair’s measurement Scintillaton-D - the detectors are based on fluoresence photon’s measurement

  6. Introduction3 §1.2 Bolometer : realy responding to energy deposit Energies for Phonons =Recoil energy +additional NpeV For scintillation medium, Y even small of a few percentage.

  7. Introduction4 §1.3 Bolometer: High energy Resolution and Low enengy threshods According to the statistics: The measurement statistics accuracy FWHM: F is Fano facctor of O (1), N is the numbers of statistics samples, w is the mean energy spent in e-h, e-ion pair and phonon production 26eV forAr-gas D 3.6eV for Si-semi.D ~meV for phonon and Quasi particle-D w = Bolometer(Micro-calorimeter) has largest samples of phonons or quasi-particles for a given Ed .So It has the highest enengy resolution and lowest energy threshold over all other detectors

  8. Introduction5 Example1 一个用蓝宝石（32克） 做吸收体，用W-TES（SPT）传感器的微量热器(@12mK) 对Al，Ti等荧光的响应(b)和它们典型的脉冲波形(a) High Resol. Low thresh. 图2.6 蓝宝石+W-TES微量热器的输出波形（a）上升，微妙，下降几毫秒（两种衰减成分） ; 以及对Al，Ti和Mn元素的特征X-射线的响应。对0.5keV谱线可见(b) Colling P, et al. Nucl. Instrum. Methods A354:408 (1995)

  9. Introduction6 §1.4 2D-readout Bolometer, High Capability to identify NR from ER events Most of dielectric crystals with a proper Debye temperture θ could be as the absorbers of Bolometer. There are three kinds of crystals could be chosen : 1. Semiconductor with diode junction : there are 2 signals produced in the absorber for one hit event: Heat signal proportional to ER and charge signal proportional to YER.(Y~0.3). 2. Scintillation crystal: there are 2 signals produced in the absorber for one hit event : Heat signal proportional to ER and fluores.signal proportional to YER.(Y~0.02). 3. Other without e-h pair and fluores.light produced Heat signal proportional to ER only (CUORE-TeO2)

  10. Introduction7 A bolometer with heat and charge signal readouts for one event Y值和反冲的类型有明显的依赖性 一个用Ge半导体探测器和NTD温度传感器@25mK 制作的双信号同时测量显示的1334个电子型反冲 （60Co伽玛）事件(黑X) 和616中子引起和反冲型 事件(灰点) 在相对电离能损(Y)和反冲动能的两维 散点图[1] ER-zone Phonon ER-zone Charge [1]D.Abrams, et al. Phys. Rev. D66, 122003 (2002)

  11. Introduction8 A bolometer with heat and fluorescensce photon signal’s readouts for one event ER-zone NR-zone 2D readouts is able to discriminate NR events from ER events G.Anglober et al.,Eur.Phys. J ,C(2012) 72:1971

  12. 2. Bolometers for Rare Event Search • A BGO bolometer Searching for Rare α-Decay • A CaWO4-Bolometer for Dark Matter Search • A TeO2-Bolometer Searching 0νββ Decay

  13. §2.1 A BGO bolometer searching for rare α-decay 一直到2003年 Orsay Cedex 实验室采用2D-BGO bolometer 确认209Bi的 α衰变之前，人们普遍认为209Bi核素是稳定的最重的天然同位素。 他们在研发用于暗物质寻找的2D读出的BGO-Bolometer时， 在复杂的背景谱中，确认了一条3.137MeV的α-谱线是有 209Bi核素发射的。 Letter to Nature 2003

  14. §2.1 NTD-heat sensor NTD-fluo. sensor

  15. §2.1 46g BGO-bolometer running 100hrs a 2D (light S.~heat S.,ER) display of background events From event scater plots a High fluo-quench NR evts are seperated fron ER-evts From Spectra b up-trace shows the mixed evts and down-trace shows evts with high fluo-quench( plot a evts under the dot-dash line 3Bq/kg 207Bi ER-evts Trace α-isotopes NR-evts Neuton BK –low energy NR-evts 3.137MeV α-line from majourity target nuclides 209Bi b Spectra of energy deposits ER of background

  16. §2.1 According the number of target nuclides of 209Bi containing in 46g-BGO bolometer and running time,courting the numbers of α-evts collected.The half life time of 209Bi T1/2=(1.9+-0.2)x1019years

  17. §2.1 1. LAS 60m altitude EC-evts of 207Bi 15,88keV ER-60CO NR-neutron Potential for D.M Search 23 51keV 2. A seperation NR-evts from ER evts is guaranteed down to 23keV(CL >90%) up to 51keV(CL.>99.99%)

  18. §2.2 A CaWO4-Bolometer for Dark Matter Search E0-ER E0 ER ( 带电+Z 的反冲核获得动能E(R)从0一直到ERMAX连续分布。而且是低反冲 动能的事件占优势 ER(θ=0)=0 ; ER(θ=180)= (1-α)E0

  19. §2.2 Spectra of N-Recoiller (Evt’s rate via ER) is Mχ -and MT’-s dependent Evt’s rates are very low: cournts /10kg year!!! Energy thresholds have to be in range of <a few tens keV N.MIRABOLFATHI , arXiv1308.0044v1 31 Jul.2013

  20. §2.2 CRESS

  21. §2.2 CA- A array of bolometers CR-Cryostat CF-A cold Finger link CR to bolometer CU-/PB-/PE:Copper/Lead/Polyethylene shield RB-Gas-tight box from Rn –gas MV-Scintillation counter Veto Cosmic rays CRESS setup CRESS

  22. §2.2 eγ-BG band One of a calbration 2D plot Neutron from AmB Low high Acc. CRESS

  23. §2.2 eγ-BG band Acc. 12.9 to40kev 6evts accepted CRESS

  24. §2.2 Acceptance: from Emin to 40keV CRESS

  25. §2.2 2D-bolometer is an able to identify various Bk CRESS

  26. §2.2 M1 Mχ=25.3GeV σwN=1.6x10-6pb M2 Mχ=11.6GeV σwN=3.7x10-5pb CRESS

  27. §2.3 A TeO2 bolometer searching for 0νββ Decay The CUORICINO is a prototype of CUORE. The target nuclide:130Te

  28. §2.3 FWHM=7keV for crystals of 5x5x5 and 9keV for one of 3x3x6 cm at 2615 keV

  29. §2.3

  30. §2.3 For 0νββ search eγ BK Is not able to discrimated But trace α-BK could be Problem if 1D only Target Nuclide be selected Q>2615keV !!

  31. §2.3 60Co(1170+1330) has to be avoided BG of the signals of 0νββ evts of 130Te 63 Cu(n,α)60Co, 2 γ from 60Co will contribute BK to the sgnals. Cu-shielder has to be store in proper place where is neutron free And make sure there is no trace of 60Co

  32. 3. Outlooks • Prelimilary consideration about DBD-search • 2D readout of an Array of bolometers • R&D of key Techs -Scintill. and thermo-sensors

  33. §3.1Prelimilary consideration about DBD-search 2νββ 0νββ 2νββ-second order weak Interac. 0 νββ-1 lepton number-violation,2 Majorana /Dirac

  34. §3.1 Basic Physics to be explored: Theory expect Experiment determination of T1/2 1 Determine the neutrino mass or set its up limit 2 Inform about the neutrino mass order 3 Information on Majorana CPV phase Invert Normal Mass order

  35. §3.1 2νββ has been observed

  36. §3.1 0νββ-not observed .set the limits to T0νββand <mν>

  37. 其中a是同位素丰度，M[kg]是衰变物质质量，W[g/mol]是同位素的摩尔质量，其中a是同位素丰度，M[kg]是衰变物质质量，W[g/mol]是同位素的摩尔质量， ΔE[keV]是附近的能窗宽度，B[keV kg y]-1是本底计数率，t[y]是测量的有效时间。 nσ是实验的标准方差数, nσ =3 ，置信水平99.73% 提高探测器在Qββ能窗区的能量分辨(ΔE小)，压低该区的背景事例率（b） 可以大大提高T0νββ的測量限。 The limits far from the expected ones by theroy ,1026~28 years So the experiment search is still long way to go

  38. §3.1 Lisa J. Kaufman arXiv:1305.3306v1

  39. §3.2 2D- readout of an Array of bolometers BK problems for experiments of the target nuclide 76Ge Qββ=2039keV Shielding lead isotopes(A=206,207 and 208) capture background neutrons become exicited isotopes 207Pb*,208Pb* and 209Pb* and contributes γ-BK between 2~3MeV. They and their escapped peaks will mimic the signals of E2β=2039keV and 63 Cu(n,α)60Co, 2 γ from 60Co will contribute BK to the sgnals.

  40. §3.2 BK problems for experiments of the target nuclide 130Te For 0νββ search eγ BK Is not able to discrimated But trace α-BK could be Problem if 1D only Target Nuclide be selected Q>2615keV !! Qββ=2615keV

  41. §3.2 60Co(1170+1330) has to be avoided BG of the signals of 0νββ evts of 130Te 63 Cu(n,α)60Co, 2 γ from 60Co will contribute BK to the sgnals. Cu-shielder has to be store in proper place where is neutron free And make sure there is no trace of 60Co

  42. §3.2 90% CL CdWO4 Energy Resol. Much worse than CUORE

  43. §3.2 FWHM ~80keV much worse than 7~9keV from the Bolometer of CUORE

  44. §3.2 FWHM=7keV for crystals of 5x5x5 and 9keV for one of 3x3x6 cm at 2615keV

  45. Task to be attacked 1. Improvent the energy resollution by using the bolometer like CUORE 2. To suppress the Alpha radiactive trace isotops BK and neutron-BK NR events could be discriminated by quenched fluo-light signals 3. Find the proper target nuclides: Qββ-keV ~3000keV Abun.% as high as possible

  46. §3.3CdWO4 as a bolometer with116Cd- target nuclides to search the rare deday A Unit of CdWO4-bolometer CdWO4 and

  47. 1+ 0+ 0+ §3.2 1.Search the neutrino-less double beta decay of Cd-nuclides(1.32x1022/cm3) ∆ -88.715 -88.248 -91.521 MeV 116Cd 116In 116Sn E2ß=Q2ß=2.806MeV Signals are larger than max BK 2.615MeV ER -BK free the nature abundence of 116Cd is 7.6%

  48. §3.3 114Cd ,A=28.8% 1+ 0+ 0+ ∆ -90.014 -88.584 -90.565 MeV 114Cd 114In 114Sn E2ß=Q2ß=0.55MeV DB events are not easy to identify from gamma-electron BG events

  49. A% 0.13 26.3 14.3 30.7 28.6 §3.3 2.Search for Alpha decay of W-nuclides(1.32x1022/cm3) According to Q,the life time were longer than 1019y and event rate were about 2~3/day. cc

  50. § 3.3 Technical issues to be attacked 1. Search for new radio-pure scintillation crystals with proper target nuclides (Qββ and Abundence)— Collab.with SIC and IOPA 2. Thermometers 0f TES (Zhou Xingxiang) and NTD sensors Collab.with IMPL 3. Cryogenic) system(Guo Guoping –Lab.of Quantum Communication USTC)

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