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Stato dell’esperimento MEG e richieste di sblocco s.j.

Stato dell’esperimento MEG e richieste di sblocco s.j. Completamento criostato: finestre sottili, guarnizioni, supporto PMT (200 K€ in C.A.) + ri -presentazione richiesta di ulteriori 110 PMT (170 K€ di C.A.) Prototipi finali del trigger e produzione di massa (100 K€ C.A.)

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Stato dell’esperimento MEG e richieste di sblocco s.j.

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  1. Stato dell’esperimento MEG e richieste di sblocco s.j. • Completamento criostato: finestre sottili, guarnizioni, supporto PMT (200 K€ in C.A.) + ri-presentazione richiesta di ulteriori 110 PMT (170 K€ di C.A.) • Prototipi finali del trigger e produzione di massa (100 K€ C.A.) • Calibrazioni: a)sorgenti alfa, b) assorbimento neutroni in Nickel, c)ulteriori possibilita’ (80 K€ in Inv.) • Elettronica per il timing counter (2 K€) Presentazione al contrario !: 1) timing counter, 2)calibrazioni, 3) trigger, 4) criostato, 5) PMT

  2. 1) Timing counter: beam test Frascati (nov 04) Beam focus sx=2.5 mm sy= 3.0 mm 5 mm Beam Geom. Select 2-electron veto

  3. Risoluzione temporale misurata

  4. From COBRA center 105 cm 25 cm 19.5º 21.5 B B Validation test in COBRA (dec 04) 98 ps Pulsed Laser Pulsed Laser 101 ps

  5. LLTh DL 1 DLY 3 & 4 S_In 2 HLTh Prototipo per la misura del tempo con discriminazione a due soglie DH Realizzazione di un modulo di elettronica NIM a 8 canali

  6. APD Ci siamo accordati per la fornitura di 1100 APD Hamamatsu nuovi attraverso CMS-PSI al costo di 70 CHF ciascuno. I 1100 sono gia’ stati consegnati al PSI e verranno presto provati a Genova.

  7. Sorces at different distances seen by each PMT: unique feature Made at Genova INFN electrodeposited ( solution) on a gold-plated W wire 0.5 mm spots 12.4 cm apart (2 PMTs) Wire thickness: 50 (alpha range ~40  ) Wire suspended with springs Wires A,B = 100 Bq/source (LP front face) Wires C,D = 30 Bq/source (LP back face) A Czech Republic firm can provide a suitable wire in which Am on foils is attached to wires by thermocompression 2) Calibrations: alpha sources spots on wires (test in LP: oct 04) LP Front face Lateral face

  8. The ring radius depends on the Rauleigh scattering length • The best value for reproducing the radius is 20 cm • In contrast with previous estimates! • Reflection ? ...we must improve the simulation and detector understanding

  9. Small displacement of the two front wires LXe GXe

  10. PMT alpha direction

  11. Charge vs Cos in LXe Front Face Data MC

  12. LXe/MC New PMTs 4 front sources Old PMTs

  13. LXe/MC 4 front sources After applying QEs

  14. Towards the final calorimeter 70 kHz photons with E>5 MeV from muon radiative decay @ R() 3x10**7. Total sources rate O(15 KBq @ 5 MeV)

  15. Trigger was changed several times … Po half-life=138 days

  16. AMERICIUM WIRE-SOURCES • World-wide search (from 2003...): • ISOTRAK-AEA TECHNOLOGY • ISOTOPE PRODUCTS • LEA-CERCA • NORTH AMERICAN SCIENTIFIC • FRAMATOME • ETC. • all of them refused to consider this custom-made product....! • too difficult, too long development, too expensive, etc. Finally:found a factory,Czech republic, Prague working on ionization smoke detectors and electrostatic charge eliminators (8 people.....) accepted to perform a R&D for our special request. UP and DOWN SUCCESS !: Production method by “thermocompression”. Liquid Nitrogen tests at ENEA. VERY IMPORTANT FOR FUTURE CRYOGENIC LIQUID DETECTORS unique feature !

  17. WIRE SOURCES FOR FINAL CALORIMETER 15 WIRES, 5 DOT-SOURCES PER WIRE 150 cm total wire length 12.4 cm distance between Am dots Central Dot 20.0 cm distance between Mark and First Dot Am dots Reference Mark Wire of 100 micron diameter Material: gold plated steel or tungsten Total length 150 cm Spacing of dot-sources 12.4 cm Linear dimension of dots 1-2 mm Activity 200Bq per dot

  18. rather narrow energy-spectra possible mounting on special supports and screws

  19. b) 9 MeV gamma line from neutron capture on Nickel:Experimental set-up • Am-Be source • (20000 n/s); • Polyethylene; • Nickel plates • 30 x 30 cm2 • (0.5 cm and 0.25 cm • thickness) • 20 x 20 x 36 cm3 • NaI detector • MCAORTEC • (2048 channels) • NIM electronics.

  20. γ-line from n-capture on Ni, I, Al, H2; natural radioactivity Tl, K; Am/Be source K 1.46 MeV H2 2.2 MeV Am/Be 4.4 MeV & 1st escape Ni 8.54 MeV & 1st escape Tl 2.6 MeV I 6.8 Mev Ni 9 MeV Al 7.7 MeV Black: Am/Be source and 1 cm Ni Red: no Am/Be source Green: no Am-Be source, no Ni (Gotta Beam on)

  21. neutron generator (Pavia ?) 20 cm 3 cm THERMAL NEUTRON CAPTURE ON NICKEL D + 2H 3He + n Q = 3.27 MeV D + 3H 4He + n Q = 17.59 MeV • Potentialities : • switchable on-off • frequent (s, m,...) stability checks • system out of the calorimeter • Ni and Xe, prompt and delayed signals • probably: visible signal at full beam intensity • time reference 9 MeV Nickelγ-line • Open problems: • monitoring from calorimeter back • only at one location ? • some dispersed neutrons and radioactivity • test of the method at high beam intensity • useful test with the “large prototype” • (already foreseen....., with Am/Be source) NaI 20 x 20 x 36 cm3 • Intensities from 106 n/s to 108 n/s • Typical pulse rate and pulse width 10 Hz and 1 μs • Time separation of direct from delayed reactions • Single pulse mode Polyethylene 0.25 cm Nickel plate

  22. Richieste sblocco 50 K€ (C.A.) per Sviluppo e produzione sorgenti Am su filo Rivelatore a Si per misura posizione sorgenti alfa Scheda MCA Rimpiazzo LiI per sfere Bonner Fogli di Boro, Polietilene, Nickel NaI da 3” con buco per alloggiamento Am/Be Elettronica lenta per lettura NaI

  23. c) ULTERIORI POSSIBILITA’ 500 KV PROTON ACCELERATOAND LITIUM TARGET FOR A 17.6 MEV GAMMA LINE 37Li (p,)48Be [P.R. 73, 666 (1948), N.P. 21 1 (1960), Zeitschrift f. Physik A351 229 (1995)] • Potentialities : • a unique nuclear reaction with a high energy -line (10 KeV) • obtainable :  106 /s (isotropic) at 440 KeV resonance (Ip 50 A) • from LiF target at COBRA center; ’s on the whole cal. entrance face • energy and position calibration; shower properties; all over LXe cal. • possibly: rather frequent use • Open problems: • compatibility with normal beam and target ? • project for easiness of target-tube mounting • accelerator/COBRA, which position and distance ? • p-beam divergence and protons on target; p29 MeV/c • 500 KeV and criticality of an air-insulated accelerator • is a post-acceleration possible ?

  24. PREVIOUS eg EXPERIMENT 1982 !!

  25. NOW: GLAST SPACE EXPERIMENT CRYSTAL CALORIMETER CALIBRATION 180 cm target-pipe It is the old VDG of the Crystal Ball experiment ! ! they have some problems: old device, max. VDG p-energy is 400 KeV out of resonance: -rate reduced by factor  5000 Stiamo discutendo sui possibili modi per l’approvvigionamento di un acceleratore adatto ai nostri scopi

  26. 3) Trigger La progettazione del PCB per le schede di tipo1 e’ entrata nella fase di routing delle connessioni, avendo quindi gia’ controllato lo schema elettrico e i footprints. La progettazione del PCB per le schede di tipo2 e’nella fase di verifica degli schemi elettrici. Con il finanziamento legato allo sblocco in oggetto, procederemo in marzo alla produzione dei PCB ed al loro montaggio per verificare le schede finali. A Luglio completeremo il test delle schede finali al PSI (milestone del trigger) e quindi potremo procedere alla produzione di massa. + contingency

  27. 4) Cryostat: designs ready; tenders and procurements organization • Tenders have been organized in three parts: • Conventional part • Cold and warm windows O. • Purchasing of the cold sealing O. • PMTs supporting structure S. • The tender procedure has been completed for the conventional part. • SIMIC has won the tender for the best price and for other reasons. • This company is going to purchase a low magnetic permeability stainless steel (<1.008) and will perform the cold test at the company. We visited the company to warn them about the project difficulty, remarking our requirements in term of level of cleanness and tightness written in the tender technical specification. • The company, if it will receive in time the cold and warm window and the cold sealing, estimated a fabrication time of 10th month. Finanziato nel 2004 (200 K€) Totale offerte e stima circa 160 K€

  28. Cold and warm windows • FEA studies are in progress. • Honeycomb structure has been discussed with manufacturing companies • We are trying to subdivide the fabrication and qualification of the window to be able to maintain the cost as low as possible • We have separated the following activities. • Mechanical test ( Mech. Dept Univ of Pisa) • Test box and welded parts (Mechanical design INFN (Pisa) manufacturing with proper company) • Tooling and molds are going to be designed by INFN (Pisa) • Honeycomb structure (Composite aerospace company)

  29. FEA studies are in progress

  30. Honeycomb structure discussed with manufacturing company Honeycomb structure Two facing of .7 mm CFRP. (intermediate high module CF with Epoxy space approved) Core aluminum honeycomb perforated This area is reinforced Internal welded foil .3 mm or less welded on external Frame necessary to test the window prior the final welding on the cryostat body. Bolted area

  31. Honeycomb structure has been discussed with manufacturing company Using thin facing material makes difficult to obtain high tolerance, even if we use a flex core material, not available in perforated aluminum. This area is reinforced Precision must been obtained on this side for this reason the honeycomb must rest on the mold on this side

  32. Cold joints: interaction with the factory Modification of bolts position and number We asked a seal no-magnetic

  33. Pisa 30-December-2004 Cold joints

  34. Struttura di supporto dei PMT: disegno pronto

  35. 4) PMTs

  36. Situazione PMT • Attualmente • 290 ZA (Pisa) • 110 TB + 4 ZA + 230 OLD (Tokyo) • Previsioni • 40 ZA rimpiazzo OLD (Tokyo) • 400 ZA nuovi (nuovo finanziamento giapponese) • Totali • 840 ZA e TB : nessuno spare (110 ZA = 170 K€)

  37. Item Cost (K€) LXe cryostat 400 PMTs test and purchase 600 Timing counter 700 Splitters 100 Trigger 400 Total 2200 Dal MoU di MEG Appendix 1. INFN contribution to the different subdetectors

  38. Stime di costo aggiornate Previsioni AssegnazioniRisparmi • LXenon • PMT 500 K€ -100K€ • Criostato200 K€ (criostato) • 160 K€ (supporto + finestre) -40K€ • Trigger • Prototipi 40 K€ • Sistema completo 100+160 K€ • -100 K€ • Timing counter • APD + fibre (interno) (160) 130K€ -30 K€ • PMT (100: esterno) (315) 135 K€ • -180 K€ • Scintillatore 50 K€ • Calibrazione 100 K€ • Meccanica60 K€ • Risparmio totale -225K€ • (rispetto ai 700 K€) • Splitters • Sistema completo 115 K€ • +15 K€ TOTALE MoU 2200 K€ Assegnato1155 K€ Previsto finale 1750 K€ Risparmio 450 K€ Non previsti: Software 22.5 K€ Calibrazioni 50 K€ PMT 170 K€ 242.5 K€

  39. Fine

  40. Zener diodes in the last two ampl. stages of the base presently installed T=-108ºC PMT with Zener

  41. Positive pulses with total positive charge are seen! (rate ~300 Hz @ V>20 mV) The problem is present ONLY at liquid Xe temperature: disappears during warm-up The pulse is not present when the Zener diodes are removed Zener problem at low temperature

  42. Several Zener diode types tried

  43. Results: FairChild

  44. What next ? • Work in closer contact with Hamamatsu: find a solution with them (test more diodes?) • Test bases in clode for longer periods • We could survive with this behaviour (only a low percentage of the events are affected) but we want to solve it before PMTs delivery • Different base schemes ?

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