Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE Double beta decay study at LNGS (the experiment LUCIFER) I. Dafinei Università "La Sapienza" di Roma and Sezione INFN - Roma made in the frame of LUCIFER experiment FP7/ ERC grant agreement n Lucifer XXIV SEMINARIO NAZIONALE di FISICA NUCLEARE E SUBNUCLEARE OTRANTO, Serra degli Alimini, Settembre 2012 Argomento : Studio del decadimento doppio beta ai LNGS Lezione 2 : Esperimento LUCIFER

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE Outline scintillating bolometers LUCIFER experiment large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers scintillating bolometers, why? device able to measure both phonon (heat) excitation and the photon (scintillation) excitation generated in a crystal by a nuclear event for a given energy deposit, the amount of emitted light is different for α wrt β/γ scatter plot light vs. heat separates α from β/γ Original idea Milano group mid 1990’s CaF 2 scintillating bolometer beta alpha The experimental basis for LUCIFER is the R&D activity lead by Stefano Pirro at LNGS, in the framework of the programs: BOLUX, funded by INFN – CSN5 ILIAS-IDEA funded by the EC (WP2-P2)

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers scintillating bolometers, how? material purity –radioactive contamination (<ppt) –chemical purity (<ppm) fabrication constraints –crystal growth, mechanical processing –package and transport (contains the 0νDBD candidate)

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers light detector (LD) performances Ge ( Ø = 35 mm) FWHM=250 eV LD: Ge disks (0.3 to 1 mm thickness) performances of a LD usually evaluated through the Energy resolution on the 55 Fe doublet (5.9 & 6.5 keV X-Ray) S. Pirro et al., "Development of bolometric light detectors for double beta decay searches", NIM A 559 (2006) 361–363

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers first scintillating bolometer (March 2004) made of a 1 cm 3 PbMoO 4 crystal glued on a copper frame and facing a 36 mm diam Ge Crystal, acting a Light Detector thermistor heater reflecting cavity Light detector

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers first scintillating bolometer S. Pirro – Cryoscint conference - Oxford, 7 Dec 2004 even if on a small sample this was the first proof of alpha discrimination on a Mo based compound

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers more on background measurement The MC simulation predicts a background level of c/keV/kg/y in the region of interest Background-Free area 2615 keV 208 Tl  44 days background Optical Materials 31 (2009) x3x6 cm3, 420 g CdWO 4

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE scintillating bolometers CdWO 4 β/β/  excellent discrimination first exhaustive explanation of the anticorrelation (bent lines) between heat and light release in a scintillating bolometer more on discrimination power C. Arnaboldi et al., "CdWO 4 scintillating bolometer for Double Beta Decay: Light and heat anticorrelation, light yield and quenching factors ", Astroparticle Physics, 34 (2010), pp

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE LUCIFER experiment technique:scintillating bolmeter LUCIFER L ow-background U nderground C ryogenics I nstallation F or E lusive R ates Principal Investigator: Fernando Ferroni ERC-2009-AdG material:ZnSe, ZnMoO 4, CdWO 4 15 kg 82 Se production Thermistor production Natural crystal (growth) R&D Enriched crystal growth Detector assembling R&D on light detectors LUCIFER timeline demonstrator isotope: 82 Se, 100 Mo, 116 Cd

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE Zn 82 Se crystal (Ø=45mm, h= 55 mm) W=483 g Reflecting Foil PTFE supports Bolometric Light Detector Ge crystal LUCIFER experiment LUCIFER in a glance array of 36÷44 enriched (95%) Zn 82 Se crystals total 82 Se nuclei: (7.1÷8.9) expected background in the ROI (2995 keV): (3÷6)10 -3 c/keV/kg/y energy resolution of the single detector expected:  10 keV FWHM location: CUORICINO (now CUORE-0) cryostat (till 2015)

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE  /  scintillation  -scintilaltion Direct ionization The  -induced background is recognized through two independent measurements: 1) the decay time of the scintillating signal 2) the different scintillation yield between  and  /  particles (the “usual” light Vs Heat scatter plot) Internal contaminations Smeared  -source 208 Tl calibration source Internal contaminations 1) Decay time of the scintillation light 2) Light Vs Heat scatter Plot ZnSe crystals shows an “inverse” QF, i.e.  -particles scintillate more than  /  ’s (Astrop. Phys. 34 (2011) ) “Ionization coincidences” between Ge light detector and ZnSe 12.5 days measurement LUCIFER experiment LUCIFER hints

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE alpha discrimination > 20 sigma ! without light detection radio-clean! LUCIFER experiment LUCIFER hints ZnMoO 4 J.W. Beeman et al., "ZnMoO4: A promising bolometer for neutrinoless double beta …", Astroparticle Physics 35 (2012) 813–820

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE Energy resolution compatible with CUORE detectors Radiopurity already at top level, no evidence of 232 Th contamination <1.4x g/g arXiv: v11  -Discrimination without light detection at 14 sigma  β/β/ Shape thermal pulse LUCIFER experiment LUCIFER hints ZnMoO 4

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE Cuore-0/Lucifer cryostat Hall C cryostat New Cryostat for Scintillating Bolometer (Oct 2012) Two above–ground (Milano Bicocca) + THREE deep underground (LNGS) LUCIFER experiment LUCIFER hints cryogenic “force”

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE 1) High Purity GErmanium – HPGE ( ,  ) LNGS 3) Neutron Activation Analysis – NAA PAVIA LENA/MiB 2) Surface Barrier Detectors – SBD (  ) LNGS/MIB 4) Inductive Coupled Plasma Mass Spectroscopy - ICPMS Direct measurement of radioactivity. The most sensitive HPGE worldwide Measurement of concentration of specific nuclei ( 238 U 232 Th) For DBD scintillating bolometers 2 ICPMS – HR ( g/g) ICPMS –HR ( g/g) LNGS + MIB LNGS LUCIFER experiment LUCIFER hints radio-purity check

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE large scale crystal production issue ~1ton TeO 2

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE Compact Muon Solenoid ~80tons PbWO 4 ~1ton TeO 2 large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE effectiveness & emission spectrum PM spectral sensitivity radiation length Molière radius  n Z eff  response time afterglow TtTt hygroscopic Hardness (Moh) Light Yield (LY) Radiaton hardness EM calorimetry High Energy Physics (HEP) bigger challenge: quantity (in HEP) is exceeded by difficulty (in REP) large scale crystal production issue extremely high sensitivity very low background Rare Events Physics (REP) main technological constraints crystal perfection radio-purity

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE large scale crystal production issue dedicated clean room Jiading dedicated crystal growth SICCAS Jiading dedicated TeO2 synthesis Kunshan Chemical Plant dedicated measurement protocols -dimensions -crystal perfection -radio-purity only 2-3% crystals can be measured precautionary principle: raw materials, reagents, intermediary products, processes and procedures dedicated production protocols -environment conditions -equipment and infrastructures -materials handling CUORE case

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE question: –is it feasible a similar enterprise in the case of scintillating bolometers? answer: –TeO2 crystal was a lucky case: industrial scale production already existed easy implementation of improvements imposed by DBD application long term existing market for high quality crystals –scintillating crystals for DBD is a more complex case: no scintillating material for DBD use was produced at large scale till now some of the problems to be addressed were solved in the case of TeO 2 crystal production work still needed for a reliable production large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE enriched Se elemental 8 URENCO, Stable Isotopes Division  instead of < preferred! SeF 6 conversion to Se through a dedicated procedure to meet DBD application requirements ZnSe synthesis and crystal growth may work as purifiers large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE ZnSe crystal growth recovery and recycling mechanical processing SmiLab (ISMA Kharkov expertise) sampleΦ[mm]H [mm] ZnSe:Sr different thermal treatment during crystal growth -chosen from a set of 11 -cryogenic test to fix the best growth conditions for maximal light output and bolometric performance ZnSe samples for cryogenic test large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE we are on the right track ! ZnSe crystal growth large scale crystal production issue

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE acknowledgements this work was made in the frame of LUCIFER experiment funded by the European Research Council under the European Unions Seventh Framework Programme FP7/ / ERC grant agreement n

Dafinei_Otranto2012_Lesson-2 Ioan Dafinei INFN Sezione di Roma, ITALY OTRANTO Settembre 2012 XXIV SEMINARIO NAZIONALE Di FISICA NUCLEARE E SUBNUCLEARE recommended bibliography 1.N. Nosengo, "Lead from ancient shipwreck will line Italian neutrino experiment",Nature (News) 15 April2010, A. Alessandrello et al., "Measurement of radioactivity of ancient roman lead...", NIM B61 (1991) C. Arpesella, "A Low Background Counting Facility at Laboratori Nazionali del Gran Sasso ", Appl. Radiat. Isot. Vol.47, No.9/10, pp (1996) 4.P.Belli et al., "Deep underground Neutron Flux Measurement with Large BF3 Counters", Il Nuovo Cimento vol. 101 A, no. 6, Giugno Ahlen S. P. et al., “Study of penetrating cosmic ray muons and search for large scale anisotropics at the Gran Sasso Laboratory”, Phys. Lett. B, Vol. 249, no.1 (1990), pp L. Cardani et al., “Performance of a large TeO2 crystal … “, JINST 7 P01020 (2012) 7.S. Pirro et al., "Development of bolometric light detectors for double beta decay searches", NIM A 559 (2006) 361–363 8.L. Gironi etal., "CdWO4 bolometers for double beta decay search", Optical Materials, Vol. 31, Issue 10, Aug. 2009, pp C. Arnaboldi et al., "CdWO4 scintillating bolometer for Double Beta Decay: Light and heat anticorrelation, light yield and quenching factors ", Astroparticle Physics, Volume 34, Issue 3, October 2010, Pages J.W. Beeman et al., "ZnMoO4: A promising bolometer for neutrinoless double beta …", Astroparticle Physics 35 (2012) 813–820 (.pdf files available upon request)