GERDA: Stato e programma C. Cattadori INFN-Milano Bicocca

CSNII, 2 Ottobre 2009 C. Cattadori -2- Outline Sensibilita’ stimata dell’esperimento GERDA (Fase I e Fase II) su T 1/2  e m ee Attivita’ Consegna ed installazione criostato Costruzione e primi tests serbatoio acqua (WT). Screening materiali Test performances e stabilita’ detector prototipo in LAr Montaggio e Primi test detector arricchiti fase I Elettronica di FE Elettronica: DAQ Slow control Attivita’ prevista per Richieste finanziarie Sblocco sub-judice 2008 Richieste 2009

CSNII, 2 Ottobre 2009C. Cattadori-3- GERDA: Collaboration ~85 physicists 15 institutions 6 countries (Europa+Russia) 6 countries (Europa+Russia) (13 ricercatori + 4 tecnologi + 1 tecnico da gruppi INFN, o associati) Location:

CSNII, 2 Ottobre 2009C. Cattadori-4- C.Cattadori

CSNII, 2 Ottobre 2009C. Cattadori-5- Location Investigation of 0  decay of 76 Ge. Location: Staged Approach (Phase I + Phase II+ …). Build a setup having a Q   cts/(kg  keV  y) adopting passive/active shielding suitable to host > 500 kg Ge detectors Use of bare diodes in cryogenic liquid (LAr) of very high radiopurity. Technique proposed by Problems reported have been overcome by GERDA collaboration. Use of bare diodes in cryogenic liquid (LAr) of very high radiopurity. Technique proposed by G. Heusser (Ann. Rev. Nucl. Part. Sci. 45(1995)543) and tested by KK in LNGS (GENIUS proposed in 2000) with non encouraging results (NIM2004). Problems reported have been overcome by GERDA collaboration. Use of detectors with improved SSE/MSE discrimination (Phase II). Goals and distinctive features of GERDA (GERmanium Detector Array)

CSNII, 2 Ottobre 2009C. Cattadori-6- Phases of GERDA Phase I: Use of existing 76 Ge-diodes from Heidelberg-Moscow and IGEX- experiments 8 detectors for 17.9 Kg of enr Ge + 15 kg nat Ge from Genius-TF Expected Background ~ count/(kg·keV·y) dominated by crystal internal backg.  KKDC evidence verified in an external background-free setup. Phase II: Add new diodes (+22 kg, total: ~40 kg enr Ge) able to discriminate SSE/MSE. Demonstration of bkg-level <10 -3 count/(kg·keV·y) Eventually Phase III: If background OK If KKDC-evidence not confirmed: O(1 ton) experiment by a worldwide collaboration with Majorana

CSNII, 2 Ottobre 2009C. Cattadori-7- GERDA: Sensitivity Assumed E resolution:  E = 4 keV phase II phase I KKDC claim GERDA I, II KK claim  if signal found in HM by KK is true  decay, this would produce in ~ 1 year GERDA I data taking (assuming 18 kg y exposure) 7 cts, above bckg of 0.5 cts  probability that bckg simulate signal ~ From Vissani, Strumia hep-ph/ v2 110 meV 270 meV

CSNII, 2 Ottobre 2009C. Cattadori-8- GERDA design Water tank (650 m 3 H 2 O) Equipped with 66 PMTs for  -veto Cryostat (70 m 3 LAr) LAr scintillation light readout can be implemented Lock for detector insertion Detector Array Cleanroom

CSNII, 2 Ottobre 2009C. Cattadori-9- GERDA:Status of Cryostat Cryostat arrived at LNGS: 6 March 2008 Rn emanation ~30 mBq (need 15 mBq)  wipe cleaning ongoing Mounting of inner Cu shielding plates (thickness 3/6 cm) completed LAr evaporation rate tested (< 2% day -1 ) LAr scintillation light readout to reduce external bckg in detectors can be implemented Cu plate being lifted at top of cryostat Cryostat installation A view inside the cryostat with Cu lining already in place Built with low activity steel 1-5 mBq/kg 6 march 2008

CSNII, 2 Ottobre 2009C. Cattadori-10- Water tank and muon veto Active shield Filled with ultra-pure water from Borexino plant 66 PMTs: Cherenkov detector Plastic scintillator on top of cleanroom 6 march 2008

CSNII, 2 Ottobre 2009C. Cattadori-11- April-May 2008 IMPORTANTE:  Collaudo WT e lavori successivi non ancora effettuato in attesa IMPORTANTE:  Collaudo WT e lavori successivi (pulizia, montaggio e cablaggio PMTs etc) non ancora effettuato in attesa autorizzazione scarico acqua GERDA in nuova rete raccolta acque di realizzazione commissariale (attesa per Ottobre 2008) (richiesta sblocco sub- judice).Realizzazione nuovo pozzetto di collegamento vs rete raccolta acque, attrezzato con riduttori di pressione e regolatori di flusso (richiesta sblocco sub- judice). Pronto progetto e computo metrico (30 kEuro) Test WT: Preliminare Test WT: Preliminare con 80 m 3 acqua poi scaricata in vasche raccolta sala A ( m 3 ) e smaltita con camions. Serbatoio acqua (WT) Ottobre-Dicembre 2008 (???)

CSNII, 2 Ottobre 2009C. Cattadori-12- Pozzetto scarico acqua GERDA

CSNII, 2 Ottobre 2009C. Cattadori-13- Impianti ausiliari ed infrastrutture Edificio (carpenteria): ultimato (LNGS) Impianti edificio: Sensori fumo,incendio, ossigeno etc commissionato (INFN fondi giunta 2007) Elettrico (progetto pronto ordine da Univ. Zurigo) Linea da impianto acqua Borexino a GERDA: commissionata (INFN) Richiesta sblocco sub-judice (2008) per filtro Ultra-Q e ricambi Impianto ricircolo acqua: Commissionato, Installazione Novembre 2008 (INFN). Richiesta sblocco sub-judice (2008) per filtro Ultra-Q e ricambi Impianto criogenia: Commissionato, Installazione Dicembre 2008-Febbraio 2009 (MPIK) Riscaldatore (ad acqua) gas Ar a perdere (per emergenza): Commissionato (MPIK) InterLock per inseriemnto detectors: Progettato ed in fase costruzione (MPPMU) Camera Pulita: Gara in corso di espletazione (MPPMU) Ventilazione di sala: in fase di definizione (LNGS) e successiva costruzione

CSNII, 2 Ottobre 2009C. Cattadori-14- Cleanroom and the lock system Prototype of Rail system for detector insertion Positioning of strings inside lock by internal rail system. Push strings to array position with magnet arms. Linear pulley system driven by motors. Control through PLC system.For Phase I a Commissioning lock will be installed

CSNII, 2 Ottobre 2009C. Cattadori-15- Results from Phase I prototypes operation (>2 y)  Handling procedures established  Optimization of thermal cyclings (> 50 cycles performed)  Low-mass detector holder tested  Detector leakage current stable and under control allowing weekly calibrations.  Observed effect of LC increase, as a consequence of  -ray irradiation understood and solved removing the detector passivation layer  Long-term stability tests : OK

CSNII, 2 Ottobre 2009C. Cattadori Co spectra: prototype detector in LAr warm 80 cm from detector Prototype detectors with modified and passivation layers performances and stability FWHM: 3.0 keV Poster n. 55 in Poster Neutrino 2008 conferences

CSNII, 2 Ottobre 2009C. Cattadori-17- Status of Phase I detectors In 2006 all IGEX (3) and HdM (8)diodes were removed from their cryostats weighted and measured to build dedicated low mass Cu- holders kg enriched and 15 kg non- enriched crystals (GENIUS-TF) available Reprocessing of all diodes at manufacturer: done in May-June Overall exposure to CR: few days /each detector Reprocessing of all diodes at manufacturer: done in May-June Overall exposure to CR: few days /each detector Always stored underground during reprocessing dead-time (HADES) Dedicated low-mass Cu holder constructed for each diode. Transported to LNGS end July 2008 August 2008: Each detector mounted in its own holder, contacted, measured forward resistivity, V-I curves, efficiency and Resolution vs HV bias. Results: All contacts OK, all (but one) V-I curves < 100 pA at operational HV, all 3<R<4 keV (with warm FE, no optimization)

CSNII, 2 Ottobre 2009C. Cattadori-18- PHASE I Front-End (FE) electronics FE CSA will be located and operated at the top of the string, i.e. in LAr at 87 K. Requirements : Low noise, low radioactivity i.e. low mass, low power consumption, operational at 87 K Few Candidates : F-CSA104 (fully integrated, poor resolution) PZ-0 (ASIC CMOS:FET,Cf,Rf not integrated), SR-1 (ASIC CMOS: Fully Integrated) IPA4 (not fully integrated, good E res,poor timing) CSA-77 (partly cold, good E res, good timing) April 2008: Comparative tests of candidates with encapsulated p-type detector PZ-0

CSNII, 2 Ottobre 2009C. Cattadori-19- Acquired output signal driving a 50  coaxial cable of ~ 10 m : rise time of ~ 15 ns Comparison between noise measured at room temperature (T=300°K) and in LN (T=77°K) Typical resolution obtained with (encapsulated) prototype crystal and cold PZ0 CSA: 2.2 keV (April ’08)(encapsulated) prototype crystal and cold PZ0 CSA: 2.2 keV (April ’08) PZ0 & detector in LAr mounted with operational holder: 3.2 keV (residual parasitic capacitance ?) (August ’08) PZ0 & detector in LAr mounted with operational holder: 3.2 keV (residual parasitic capacitance ?) (August ’08) Results: ASIC CMOS developed by INFN-Milano group chosen, as provides best timing and noise performances

CSNII, 2 Ottobre 2009C. Cattadori-20- Elettronica di FE: circuiti ASIC CMOS con J-FET non integrato esterno, Rf e Cf esterni C comp =1pF C comp =1.4pF Chip a 3 canali, PCB in fase di design e realizzazione Chip ad 1 canale montato in carrier ceramico su PCB testato in estate 2008

CSNII, 2 Ottobre 2009C. Cattadori-21- Altre attivita’ legate a read-out e pulse processing In collaborazione con M.Nicoletto servizio elettronica INFN-PD, ridefinizione tecnologia ICARUS per connettori sigillati HV per HVbias =+4kV in vapori di LAr, per specifiche GERDA (corrente dispersa vs. GND ~10 pA). Grosso problema risolto! Prodotti i primi 4 passanti a 4 canali ognuno, testati OK! Trovato e di adeguata radiopurezza materiale per PCB, cavo coax per segnali, LV e HV. Trovato e di adeguata radiopurezza materiale per PCB, cavo coax per segnali, LV e HV. Implementata FPGA in sistema DAQ-FADC (14 bit, 100 MHZ) sviluppato a PD/Legnaro (C. Ur) Implementata FPGA in sistema DAQ-FADC (14 bit, 100 MHZ) sviluppato a PD/Legnaro (C. Ur) In via di sviluppo implementazione soglia digitale in FPGA in FADC Fase I. In via di sviluppo implementazione soglia digitale in FPGA in FADC Fase I.

CSNII, 2 Ottobre 2009C. Cattadori-22- Stato dello slow control Lo Slow Control per GERDA viene sviluppato sulla base dell’esperienza fatta con lo Slow Control di OPERA, specializzato alle esigenze specifiche di GERDA. Compiti principali: : Controllo degli alimentatori bassa e alta tensione; Controllo dei parametri operativi principali: temperatura, leakage current, etc.; Lettura di tutti i parametri dei rivelatori di GERDA e archiviazione in un database; Produzione e gestione di allarmi; Interfaccia grafica e monitoraggio dello stato dei rivelatori; Istogrammi temporali dei parametri monitorati; Controllo remoto; Integrazione di tutti i sistemi locali di Slow Control; 2.Sviluppo e realizzazione di connessioni di rete sicure tra tutte le componenti di GERDA nel laboratorio sotterraneo e comunicazione con i laboratori remoti

CSNII, 2 Ottobre 2009C. Cattadori-23- GERDA. Diagramma a blocchi dello SC generale 1. Database – archivio dei dati dello SC e delle configurazioni sperimentali (usa database PostgresSQL)  Database temporaneo – una settimana di backlog  Database storico – archivia l’insieme completo di parametri 2.Clients – per ogni dispositivo hardware ci sarà un client che acquisisce i parametri e li carica sul database dello SC 3.Alarm manager – recupera i dati dal database, li analizza e genera avvertimenti e allarmi in caso di malfunzionamento 3.Visore di istogrammi, visore di allarmi 4.Allarmi di sicurezza – trasmessi al sistema generale di sicurezza del LNGS Wiener VME Crate monitoring Già operativo

CSNII, 2 Ottobre 2009C. Cattadori-24- Attivita’ Test front-end criogenico a 3 ch Al banco (Mi) Con detector incapsulato acquistato su fondi 2008 (MiB) Con detector nudo (MiB). Comprensione e mitigazione capacita’ parassite residue per migliorare la risoluzione (da connessione con FE, da montaggio/contatto detector?) Completamento implementazione FPGA in FADC readout e trigger digitale. Installazione e start-up impianti a servizio WT e criogenia Screening materiali (ICPMS, g-ray) Migrazione (obbligatoria) tecnologia FE a silicio 0.35  m (tecnologia 0.5  m dismessa dalla fonderia) Commissioning GERDA previsto per il secondo trimestre Inizio presa dati: ~ Nel corso del terzo trimestre Necessita’ di supporto della Sezione per avvio attivita’ GERDA

CSNII, 2 Ottobre 2009C. Cattadori-25- Attivita’ Start-up attivita’ SiPM per read-out LAr con device radiopuri per abbattimento fondo (veto detector con luce scintillazione LAr) Test stringhe di detector in LARGE a LNGS) Attivita’ con detector Be-Ge a MiB Per test front-end Per test di una possibile configurazione detector fase II. Questa ultima attivita’ si integra nelle attivita’ che fervono nella collaborazione, gia’ in possesso di 38 kg di enr Ge, per la deifinizione della tecnologia e della ditta o istituto di ricerca che possa Crescere con alto yield ed a prezzi non da monopolio i cristalli arricchiti per la Fase II Definizione del miglior detector di fase II per migliorare la reiezione dei MSE vs SSE. P-type, n-type, segmentato, Be-GE, point-contact etc. Ricordo che la collaborazione GERDA si e’ formata sul progetto FaseI&FaseII, esso e’ stato scientificamente approvato da tutti I comitati di review (SC-LNGS,CSNII,MPIK,MPPMU etc). La commissione II non aveva a suo tempo accettato il piano proprosto dai gruppi italiani, chiedendo di rinviare la discussione a data da destinarsi, invitando la collab italiana a rinforzarsi e a dare il via ai lavori.

CSNII, 2 Ottobre 2009C. Cattadori-26-

CSNII, 2 Ottobre 2009C. Cattadori-27-

CSNII, 2 Ottobre 2009C. Cattadori-28- Phase II crystal pulling  enr Ge purchased (37.5 kg) presently stored at HADES  Activities related to crystal pulling started on nat Ge PPM for GeO 2 purification IKZ (Berlin) for crystal pulling  nat GeO 2 reduced to metal bars and purified to 6N material for Czochralski pulling  No impurities detected with ICPMS measurements  First crystal IKZ Berlin, characterization will follow

CSNII, 2 Ottobre 2009C. Cattadori-29- Phase II: Results with prototype detectors A possible segmentation scheme is 18 fold (6  x 3 z). Tested contacting technique: it works in cryogenic liquid. First spectra taken with core and all 18 segments. Energy resolution(core): ~ 4 1.3MeV (preliminary). We are considering the use of point contact detectors: much simpler readout. First PS studies encouraging!

CSNII, 2 Ottobre 2009C. Cattadori-30- All events Single segment events Double Escape Peak (mostly SSE) Photon Peak (mostly MSE) All events Single segment events Phase II: Results with prototype detector Study of 208 Tl Double Escape keV= 1592 keV Compton Background Suppression Q  : ~ 3 Agreement with MC

CSNII, 2 Ottobre 2009C. Cattadori-31- GERDA: Background evaluation and reduction SourceActions  ’s from external environment 208 Tl and 214 Bi Shield with hyperpure liquids (H 2 O 3 m+LAr 2 m) 3  10 –5 kg –1 y –1 keV –1  3  10 –5 kg –1 y –1 keV –1 228 Th (<10 mBq/kg) in Cryostat (SS) HP Cu shield (25 µBq/kg; cm thick)+LAr µ induced prompt signals ~1400 m rock overburden Anticoincidence between crystals(&segments) µ-vetoes: top (plastic scint.) +Water Cherenkov 10 –4 kg –1 y –1 keV –1  10 –4 kg –1 y –1 keV –1 µ induced delayed signals n+ 76 Ge  77m Ge  77 As (t 1/2 = 53 s) Low-Z shields 10 –4 kg –1 y –1 keV –1 Delayed concid. Tag decay chain  10 –4 kg –1 y –1 keV –1 Internal to crystals Cosmogenic 60 Co (t 1/2 = 5.27 y) (crystal production) Minimize time above ground after crystal growing Diode & segments antic., PSA 3.5  10 –5 kg –1 y –1 keV –1  3.5  10 –5 kg –1 y –1 keV –1 Internal to crystals Cosmogenic 68 Ge (t 1/2 = 270 d) (crystal and detector productions) Minimize time above ground after enrichment; shielded transport container 5  10 –4 kg –1 y –1 keV –1 After two years underground  5  10 –4 kg –1 y –1 keV –1 Reduce by segmentation and PSA Front-end electronics, cables, support 5  10 –4 kg –1 y –1 keV –1 Materials minimisation (grams) & selection. Still under R&D   5  10 –4 kg –1 y –1 keV –1

CSNII, 2 Ottobre 2009C. Cattadori-32- Schedule of forthcoming activities ( ) Water Tank & PMTs for  -veto water Cerenkov May-June Technical Building & Superstructure: Summer 2008 Lock & Clean Room: Commisioning: ~ first semester 2009 Commisioning: ~ first semester 2009 In parallel: Complete Reprocessing of all Phase I crystals, assemble 3-fold strings, integrate cold FE with detector string, etc…………….

CSNII, 2 Ottobre 2009C. Cattadori-33- Extra slides

CSNII, 2 Ottobre 2009C. Cattadori-34- The neutrino masses and mixings angles We know from atmospheric, solar and reactor neutrino experiments that Neutrino flavour eigenstates ≠ neutrino mass eigenstates  m 2 ≠ 0. Measured values  12 = 34.1˚±1.5˚  23 = 42˚+4.6˚/–2.5˚  13 < 8˚ Fitted values |  m2|= 2600±180 meV 2 (8%)  m2 = 79.2±3.6 meV 2 (4.5%) We don’t know absolute neutrino mass value and hyerarcy i.e. sign of  m 2  m atm 2 =m 3 2 – (m 2 2 +m 1 2 )/2

CSNII, 2 Ottobre 2009 C. Cattadori -35- Heidelberg-Moscow LNGS: claim of evidence of 0  of 76 Ge (2004) Claimed evidence of  T 1/2 =  1.2 x  y Corresponding to M ee = 440 meV with KK ME 214 Bi  ? Signal found at Q  exp = ± 0.44 keV Q   theo  ± 0.05 keV MT = 10.9 kg (86% 76 Ge) x 13 yr x 0.8% = 72 kg yr b = 0.11 cts/(kg keV yr) before PSA Resolution  = 3.27 keV

CSNII, 2 Ottobre 2009 C. Cattadori -36- IGEX Collaboration: (ITEP,INR,U.South Carolina; PNNL, U. of Zaragoza, Yerevan) Location: Canfranc UL (Spain) Pulse shape discrimination 117 mol. y = 8.9 kg. y Bkg at 2 Mev  0.1 (with PSA) / 0.2 (without PSA) [cts/(keV. y)] Enriched Ge diodes T ½ > y with PSA T ½ > y with PSA M ee < eV M ee < eV Q 

CSNII, 2 Ottobre 2009C. Cattadori-37- Materials & Assay - Additional improvements have been gained in producing pure Cu through electroforming at PNNL and we have established an operating pilot program demonstrating electroforming underground at WIPP. Ge Enrichment - Options available for germanium oxide reduction, Ge refinement, and efficient material recycling are being considered, including developing this capability located near detector fabrication facilities. Additional p-type point contact (PPC) detectors have been ordered. Progress has been made in E-M modeling. A PPC detector has been successfully fabricated at the LBNL Instrument Support Laboratory Detectors - Additional p-type point contact (PPC) detectors have been ordered. Progress has been made in E-M modeling. A PPC detector has been successfully fabricated at the LBNL Instrument Support Laboratory. Efforts to deploy a prototype low-background N-type segmented contact (NSC) detector using our enriched SEGA crystal are underway. This will allow us to test low-mass deployment hardware and readout concepts while working in conjunction with a detector manufacturer. Cryostat Modules - A realistic prototype deployment system has been constructed at LANL. First measurements, with one string and a single P-type HPGe detector have been completed. DAQ & Electronics Facilities - Designs for an underground electroforming facility and a detector laboratory located on the 4850’ level in the Homestake Mine have been developed in conjunction with SUSEL engineers. MAGE Simulations - Several papers describing background studies have been published and our simulation framework has been submitted for publication (joint effort with GERDA). MAGE MAJORANA technical progress - past year

CSNII, 2 Ottobre 2009C. Cattadori-38- bb searches of 76 Ge by germanium detectors: pioneering experiments Adapted from Elliot & Vogel

CSNII, 2 Ottobre 2009C. Cattadori-39- Nuclear matrix

CSNII, 2 Ottobre 2009C. Cattadori-40- Assumption for GERDA I FWHM= 3.6 keV,  = 95% M =15 kg (86% enriched) t = 1 year  Effective Ge mass = 15· 0.86 kg y B tot =B ext (10 -3 cts/(kev · kg · y))+B int (10 -2 cts/(kev · kg · y)) = 0.5 counts  if no counts happens (60% chance) T 1/2 > 3.0 ·10 25 at 90% CL, m ee < 0.24 –0.77 eV   claim ruled out at 99.6% CL  if non-zero counts (  =0.5 counts Poissonian fluctuated) T 1/2 > 2.2 ·10 25 at 90% CL, m ee < 0.28 –0.9 eV (if 1 cts  claim ruled out at 97.8% CL)  if signal found in  HM is true  decay, this would produce in GERDA I (= 15 kgy) 6 ± 1.4 cts, above bckgrd of 0.5 cts  5  confirmation GERDA I Physics reach

CSNII, 2 Ottobre 2009C. Cattadori-41- With new segmented detectors and keeping the isotope separation+ crystal growing time within 180 days  B ~ cts /(keV kg y) With mass of 40 kg y x 3 years FWHM = 3.6 keV  B = 0.36 background counts expected T 1/2 > 2.0 ·10 26 at 90% CL, m ee < 0.09 –0.29 eV GERDA II Physics reach