Stefano Pirro - CSNII – 29 Sett 2010 Stefano Pirro Lucifer-RD - Milano CSNII, Roma 29 Settembre 2010

Stefano Pirro - CSNII – 29 Sett 2010 Environmental “underground” HPGE Background: 238 U and 232 Th trace contaminations Motivazioni CUORICINO  Background 130 Te 76 Ge 100 Mo 116 Cd Lo scopo è duplice…. Abbattere la radioattività  e scegliere un nuclide più favorevole  -region  -region 82 Se

Stefano Pirro - CSNII – 29 Sett 2010 Principles of operation  =C/G  T=  E/C A Bolometric Light Detector is fully active massive particle detector The QE of a BLD is, probably, comparable with that one of PD’s but it is not easy to measure it The time response of a BLD is the same of a standard bolometer O (ms) Normally PURE (undoped) Ge or Si crystal are used as absorbers

Stefano Pirro - CSNII – 29 Sett 2010 La tecnica è nata “tanti anni fa…” During April 2005 a background measurement was performed with the RAD detector 417 h live time measurement S. Pirro - Scintillating Double Beta bolometers NANP05 Dubna 23 June 2005

Stefano Pirro - CSNII – 29 Sett 2010 Scintillating bolometers and ”official” funding The activity was officially funded by INFN through the BoLux (R&D) Experiment* and by EC Ilias (FP6) * Responsible: Stefano Pirro The CUPIDO R&D* project (INFN) was accepted by CSN5 for 2010 (total 3.4 FTE) but was hardly cut by referees. The Bolux group (1.5 –1.8 FTE) was originally formed by INFN-Mi-Bicocca In 2007 I asked for an EC Starting grant to perform a small Experiment based on CdWO 4 but the project was badly rejected - “essential weaknesses in the proposal “ BoLux was “extended” for 2009 with the join of Roma 1 (total 2.6 FTE) A “PRIN” was presented to MIUR in 2009 but was rejected The activity of Scintillating bolometers is inserted in ILIAS-NEXT (FP7) proposal with a request of money of 300 k€ …. But also Ilias Next was Rejected …….  Lucifer was approved by ERC (Ferroni)

Stefano Pirro - CSNII – 29 Sett 2010 Li 2 MoO 4 ZrO 2 Good Scintillation lightPoor Scintillation light No Scintillation light MgMoO 4 TeO 2 Summary of (almost) all the measured crystals ZnSe PbMoO 4 SrMoO 4 CdMoO 4 CdWO 4 CaF 2 CaMoO 4 ZnMoO 4

Stefano Pirro - CSNII – 29 Sett 2010 Lucifer E’ un ERC – Advanced Grant assegnato a F.Ferroni per costruire un prototipo di rivelatore scitnillante per il DDB Il valore del Grant è € su un periodo di 5 anni (Marzo 2010 –Marzo 2015) MI=190 k€ ME=110 k€ Cons=1780 k€ INV=30 k€ Pers= 637k€

Stefano Pirro - CSNII – 29 Sett 2010 La “scelta” dello ZnSe per Lucifer La Scelta dello ZnSe è stata dettata da diversi fattori  Sicuramente è quello che ha più speranze di essere sviluppato nel tempo del progetto dell’ ERC  Sembra avere caratteristiche (bizzarre) decisamente migliori rispetto a tutti gli altri composti

Stefano Pirro - CSNII – 29 Sett 2010 Lo ZnSe Lo ZnSe è un composto piuttosto bizzarro….. Noto come uno dei migliori scintillatori esistenti, Ma con una lunghezza di attenuazione piuttosto risibile Massa= 340 g Dimensioni dia=4 h=5

Stefano Pirro - CSNII – 29 Sett 2010 Calibration with 232 Th and a smeared  source 210 Po Beta region Rejection > 99.5 % Smeared  source Light ZnSe – Scatter Plot + Light PSA // 

Stefano Pirro - CSNII – 29 Sett 2010 ZnSe – Heat PSA This compound shows another very interesting feature:  ’s show different thermal pulse development //   rejection > 97 % without light detection

Stefano Pirro - CSNII – 29 Sett 2010 ZnSe – The best case (140 g crystal) Light signal /β/β  /β/β  /β/β  Separazione > 15 σ

Stefano Pirro - CSNII – 29 Sett 2010 I due Item di Lucifer Gli Item di Lucifer possono dividersi in 2  Arricchimento isotopico  Sviluppo e crescita dei cristalli

Stefano Pirro - CSNII – 29 Sett 2010 Arricchimento isotopico Materiale preferito 82 Se Quantità > 15 Kg Budget 1.2 Meuro Tempo < 3 anni

Stefano Pirro - CSNII – 29 Sett 2010 Dove arricchire Tradizionalmente Krasnojarsk (ex città chiusa dell’URSS) In Russia c’è anche Tomsk In Europa occidentale c’è URENCO

Stefano Pirro - CSNII – 29 Sett 2010 I problemi e le prospettive I russi hanno centralizzato gli ordini tramite RUSSATOM Difficoltà di comunicazione Il tradizionale intermediario (CHEMGAS, Fr) che ha funzionato per NEMO3 è stato fatto fuori Abbiamo in mano un modulo che ci chiede quanto vogliamo pagare e che comunque dobbiamo pagare tutto in anticipo

Stefano Pirro - CSNII – 29 Sett 2010 URENCO Una sola frase : Currently, forward orders stand in excess of 20 billion Euro and extend beyond Abbiamo chiesto la carità !!!! Forse funziona, more news alla fine del mese Hanno una parte del SeSF 6 Stanno cercando il resto Devono migliorare la chimica (throughput) Siamo vincolati a un ‘non disclosure agreement’

Stefano Pirro - CSNII – 29 Sett 2010 R&D for the obtainment of ZnSe crystals for double-beta decay application 1.Optimization of ZnSe crystal growth and post-growth treatment conditions preparation and analysis of several (small) crystals in different conditions production of large crystals in selected conditions cryogenic test of large size crystals 2.Determination of ZnSe production yield in view of 82 Se enriched crystal growth dedicated production line for ZnSe synthesis dedicated crystal growth recycling estimate possible growth of a ZnSe crystal using 82 Se enriched material 3.Finding the nature of the anomalous quenching effect in ZnSe growth and study of other A II B VI compounds growth of Sm doped ZnSe crystal 4.Setting the certification protocol for series production of ZnSe crystals determination of acceptable radio-active impurities level finding a scintillation efficiency test applicable at room temperature INFN Order (INFN_Order-1800_10.pdf) for the delivery of 4 large crystals (Ø25mm, h25mm) and related twin samples for the study of optical properties. Delivery foreseen within mid October. The 4 crystals are: -ZnSe prepared in different post growth conditions (enriched Zn atmosphere): 2pcs -ZnTe for the study of the α/  quenching factor in a fully covalent A II B VI compound -ZnSe:Sm for the study of the α/  quenching factor

Stefano Pirro - CSNII – 29 Sett 2010 Though the setup from scratch of a fully equipped laboratory for the study of materials for particle detectors (scintillating crystals and glasses, Cherenkov detectors, bolometers, etc) is a task far beyond the possibilities offered by a single experiment in CSN-II, a basic equipment could be procured within affordable cost limits, possibly in the frame of a farsighted equipment program. 1. Optical transmission measurement setup (quasi gratis….) Measuring the optical transmission allows the study of possible ways to improve the absorption length and consequently the measured LY of a scintillator. This measurement is crucial specially in the case of crystals supposed to be used at low temperature given the well known effect of optical absorbtion edge shift with the temperature. The old Perkin Elmer Lambda 18 UV VIS Spectrophotometer existing at LNGS (Laboratorio di Chimica) may be used as a temporary solution. Small modifications of the measuring compartment are needed for the measurement of temperature dependence of optical properties using a cryocooler (see below). Lack of a dedicated structure for the study of scintillating materials 2. Cryocooler (è un MUST) The necessity to have such an instrument is obvious for a research program dedicated to cryogenic bolometers. Nevertheless it should be specified that for material research purpose, a relatively small capacity cryostat (typical sample dimensions: 1x1x1 cm 3 ) would be sufficient. A measuring chamber provided with at least 3 optical windows will be needed which would allow the measurement of optical properties of the samples.

Stefano Pirro - CSNII – 29 Sett Time resolved spectroscopy (è un MUST legato al cryocooler) Various methods may be used for the measurement of scintillation decay time (e.g. using a gated charge sensitive amplifier in a LY setup). The most commonly used method for precise measurements of scintillation decay spectra is the "single photon method" (Bollinger and Thomas). The temperature dependence of the decay time gives fundamental information on the scintillation mechanism and possible improvements of the light yield. A decay time measurement bench can be easily be realized using as main component the cryocooler mentioned at the point 2. The minimal supplementary equipment needed would be: 2 PMs and associated electronics (power supply, TDC, MCA, etc) and a pc for the measurement control. 5. Set-ups which could be built locally (quasi gratis….) Light Yield (LY) Photoconductivity (useful specially in the case of A II B VI compounds where scintillation properties are strongly correlated with non-equilibrium carrier dynamics 3. Photo and radio-luminescence (al momento è un sogno…) The photoluminescence spectra are usually obtained with commercially available spectro-fluorimeters where different excitation sources may be used. In most cases the photoluminescence and radioluminescence emission spectra of a material are the same. Nevertheless even in the case where the two spectra should be the same, important difference may be noticed due to the fact that in the case of radioluminescence the emission centres are excited in the bulk of the material and consequently the contribution of the reabsorption may be very high. Usually home made set-ups are used for the study of the radioluminescence spectra specially for new materials.

Stefano Pirro - CSNII – 29 Sett 2010 Richieste in CSN II I fondi Europei NON pagano missioni di laureandi e, sopratutto, Dottorandi I fondi Europei pagano parte dell’inventariabile 7.5 Apparati= criostato 10 K per misure di scintillazione a bassa temperatura + 2 PM (bialkalii) +MCA 28 $ =20 k€ 4 k€ Totale inventariabile=28 k€ Ammortamento 2/5 ? Totale inventariabile= 11.2 k€ Totale richieste = 15 k€ + 3 k€ + … 11.2 k€ = 29.2 k€

Stefano Pirro - CSNII – 29 Sett 2010 The dimensions of the optical sample holder are compatible with the size of the measuring chamber of the spectrophotometer existing at LNGS (Perkin Elmer Lambda 18 UV-VIS) Cryocooler

Stefano Pirro - CSNII – 29 Sett 2010 Frizioni/sinergia con CUORE Un MoU “interno è stato stipulato tra CUORE e Lucifer riguardante il criostato R&D di Sala C  L’utilizzo del criostato di CUORE 0 (fine ?) per l’esperimento non è per ora affrontato  Il “tempo macchina” è stato allocato INDICATIVAMENTE ¼ ¾ con precedenza a CUORE  Sono già stati banditi 2 AdR di persone che continueranno a lavorare su CUORE (+1 in discussione)  Lucifer pagherà una buona parte della costi di manutenzione del laboratori di sala C