1 A, Baldini, Roma 1 Febbraio 2005 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 A, Baldini, Roma 1 Febbraio ) Timing counter: beam test Frascati (nov 04) Beam focus  x=2.5 mm  y= 3.0 mm 5 mm Beam Geom. Select 2-electron veto

3 A, Baldini, Roma 1 Febbraio 2005 Risoluzione temporale misurata

4 A, Baldini, Roma 1 Febbraio 2005 Validation test in COBRA (dec 04) 19.5º 21.5 From COBRA center 105 cm25 cm B B Pulsed Laser 101 ps 98 ps

5 A, Baldini, Roma 1 Febbraio 2005 Prototipo per la misura del tempo con discriminazione a due soglie DHDH DHDH HLTh DLDL DLDL & & DLY LLTh S_In Realizzazione di un modulo di elettronica NIM a 8 canali

6 A, Baldini, Roma 1 Febbraio 2005 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 2) Calibrations: alpha sources spots on wires (test in LP: oct 04) 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 LP Front faceLateral face

8

9 A, Baldini, Roma 1 Febbraio 2005 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

10 Small displacement of the two front wires LXeGXe

11 PMT alpha direction

12 Charge vs Cos  in LXe Front Face DataMC

13 LXe/MC New PMTs Old PMTs 4 front sources

14 LXe/MC After applying QEs 4 front sources

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

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

17 A, Baldini, Roma 1 Febbraio 2005 AMERICIUM WIRE-SOURCES World-wide search (from ): 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 !

18 A, Baldini, Roma 1 Febbraio 2005 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  200 Bq per dot 150 cm total wire length Am dots 12.4 cm distance between Am dots Reference Mark 20.0 cm distance between Mark and First Dot Central Dot WIRE SOURCES FOR FINAL CALORIMETER 15 WIRES, 5 DOT-SOURCES PER WIRE

19 A, Baldini, Roma 1 Febbraio 2005 rather narrow energy-spectra possible mounting on special supports and screws

20 A, Baldini, Roma 1 Febbraio 2005 b) 9 MeV gamma line from neutron capture on NickelExperimental set-up b) 9 MeV gamma line from neutron capture on Nickel:Experimental set-up - Am-Be source (20000 n/s); (20000 n/s); - Polyethylene; - Nickel plates 30 x 30 cm 2 30 x 30 cm 2 (0.5 cm and 0.25 cm (0.5 cm and 0.25 cm thickness) thickness) - 20 x 20 x 36 cm 3 NaI detector NaI detector -MCA ORTEC (2048 channels) (2048 channels) - NIM electronics.

21 A, Baldini, Roma 1 Febbraio 2005 γ-line from n-capture on Ni, I, Al, H 2 ; natural radioactivity Tl, K; Am/Be source Am/Be 4.4 MeV & 1 st escape I 6.8 Mev Al 7.7 MeV Ni 9 MeV Ni 8.54 MeV & 1 st escape H MeV Tl 2.6 MeV Black: Am/Be source and 1 cm Ni Red: no Am/Be source Green: no Am-Be source, no Ni (Gotta Beam on) K 1.46 MeV

22 A, Baldini, Roma 1 Febbraio MeV Nickel γ-line NaI 20 x 20 x 36 cm 3 neutron generator (Pavia ?) Intensities from 10 6 n/s to 10 8 n/s Typical pulse rate and pulse width 10 Hz and 1 μs Time separation of direct from delayed reactions Single pulse mode THERMAL NEUTRON CAPTURE ON NICKEL 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 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) D + 2 H  3 He + n Q = 3.27 MeV D + 3 H  4 He + n Q = MeV Polyethylene 0.25 cm Nickel plate 3 cm 20 cm

23 A, Baldini, Roma 1 Febbraio 2005 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

24 A, Baldini, Roma 1 Febbraio 2005 c) ULTERIORI POSSIBILITA’ 500 KV PROTON ACCELERATOAND LITIUM TARGET FOR A 17.6 MEV GAMMA LINE Potentialities : a unique nuclear reaction with a high energy  - line (  10 KeV) obtainable :  10 6  /s (isotropic) at 440 KeV resonance (I p  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 ? [P.R. 73, 666 (1948), N.P (1960), Zeitschrift f. Physik A (1995)] 3 7 Li (p,  ) 4 8 Be

25 A, Baldini, Roma 1 Febbraio !! PREVIOUS   e  EXPERIMENT

26 A, Baldini, Roma 1 Febbraio 2005 NOW: GLAST SPACE EXPERIMENT CRYSTAL CALORIMETER CALIBRATION 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 180 cm target-pipe

27 A, Baldini, Roma 1 Febbraio ) 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

28 A, Baldini, Roma 1 Febbraio ) Cryostat: designs ready; tenders and procurements organization Tenders have been organized in three parts: 1.Conventional part 2.Cold and warm windows O. 3.Purchasing of the cold sealing O. 4.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 10 th month. Totale offerte e stima circa 160 K€ Finanziato nel 2004 (200 K€)

29 A, Baldini, Roma 1 Febbraio 2005 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)

30 A, Baldini, Roma 1 Febbraio 2005 FEA studies are in progress

31 A, Baldini, Roma 1 Febbraio 2005 Honeycomb structure discussed with manufacturing company 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 This area is reinforced Honeycomb structure Two facing of.7 mm CFRP. (intermediate high module CF with Epoxy space approved) Core aluminum honeycomb perforated

32 A, Baldini, Roma 1 Febbraio 2005 Honeycomb structure has been discussed with manufacturing company Precision must been obtained on this side for this reason the honeycomb must rest on the mold on this side 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

33 A, Baldini, Roma 1 Febbraio 2005 Cold joints: interaction with the factory Modification of bolts position and number We asked a seal no-magnetic

34 A, Baldini, Roma 1 Febbraio 2005 Pisa 30-December-2004 Cold joints

35 A, Baldini, Roma 1 Febbraio 2005 Struttura di supporto dei PMT: disegno pronto

36 A, Baldini, Roma 1 Febbraio st generation R6041Q2 nd generation R9288TB3 rd generation R9288ZA 228 in the LP (2003 CEX and TERAS) 127 in the LP (2004 CEX) 111 In the LP (2004 CEX)Not used yet in the LP Rb-Sc-Sb Mn layer to keep surface resistance at low temp. K-Sc-Sb Al strip to fit with the dynode pattern to keep surface resistance at low temp. K-Sc-Sb Al strip density is doubled. 4% loss of the effective area. 1 st compact version QE~4-6% Under high rate background, PMT output reduced by % with a time constant of order of 10min. Higher QE ~12-14% Good performance in high rate BG Still slight reduction of output in very high BG Higher QE~12-14% Much better performance in very high BG 4) PMTs

37 A, Baldini, Roma 1 Febbraio 2005 Situazione PMT Attualmente 290 ZA (Pisa) 110 TB + 4 ZA 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€)

38 A, Baldini, Roma 1 Febbraio 2005 Dal MoU di MEG Appendix 1. INFN contribution to the different subdetectors ItemCost (K€) LXe cryostat400 PMTs test and purchase 600 Timing counter700 Splitters100 Trigger400 Total 2200

39 A, Baldini, Roma 1 Febbraio 2005 LXenon PMT 500 K€ -100K€ Criostato 200 K€ (criostato) 160 K€ (supporto + finestre) -40K€ Trigger Prototipi 40 K€ Sistema completo K€ -100 K€ Timing counter APD + fibre (interno)(160) 130K€ -30 K€ PMT (100: esterno)(315) 135 K€ -180 K€ Scintillatore 50 K€ Calibrazione100 K€ Meccanica 60 K€ Risparmio totale -225K€ (rispetto ai 700 K€) Splitters Sistema completo 115 K€ +15 K€ TOTALE MoU 2200 K€ Assegnato1155 K€ Previsto finale1750 K€ Risparmio 450 K€ Stime di costo aggiornate Previsioni Assegnazioni Risparmi Non previsti: Software 22.5 K€ Calibrazioni 50 K€ PMT 170 K€ K€

40 A, Baldini, Roma 1 Febbraio 2005 Fine

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

42 Zener problem at low temperature Positive pulses with total positive charge are seen! (rate ~300 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

43 Several Zener diode types tried SellerBrandPackage DistrelecFairChildGlass FarnellPhillipsplastic RS On semicond plastic RSPhillipsCeramic Original...plastic RSVishaysinter gl.

44 Results: FairChild Hz Hz (75//75)x23 Hz

45 A, Baldini, Roma 1 Febbraio 2005 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 ?