1. 1 February 9th 2005 LXe calibrations, PMT tests, cryostat construction 1. Alpha sources on wires 2. 9 MeV  from neutron capture in Nickel 3.  0 4. further calibration methods ? 5. PMTs tests 6. Cryostat status Calibrations

2. 2 1) Alpha sources spots on wires 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

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5. 5 February 9th 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

6. 6 Small displacement of the two front wires LXeGXe

7. 7 PMT alpha direction

8. 8 Charge vs Cos  in LXe Front Face DataMC

9. 9 LXe/MC New PMTs Old PMTs 4 front sources

10. 10 LXe/MC After applying QEs 4 front sources

11. 11 70 kHz photons with E>5 MeV from muon radiative decay @ R(  ) 3x10**7. Total sources rate O(15 KBq @ 5 MeV) Towards the final calorimeter

12. 12 Po half-life=138 days Trigger was changed several times …

13. 13 February 9th 2005 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 !

14. 14 February 9th 2005 SPECITICATIONS AND CONTRACT FOR THE PRODUCTION OF Am WIRE-SOURCES AND OF Am DISK-SOURCES Ready: end of March 2005 (TOTAL ACTIVITY < 40 kBq) Each dot-source: small radioative foil fixed on wire by “thermocompression” TESTED AT NITROGEN TEMPERATURE AT THE ENEA LAB. IN ROME. OK ! NEEDED FROM PSI: Authorization of nuclear security for products Authorization for import of radioactive sources Auhorization for production of detectors using radioactive sources

15. 15 February 9th 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

16. 16 February 9th 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 Wire centre WIRE SOURCES FOR LARGE PROTOTYPE 10 WIRES, 2 DOT-SOURCES PER WIRE

17. 17 February 9th 2005 Wire of  100 micron diameter Material: gold plated steel or tungsten Total length 50 cm Central dot-source Linear dimension of dots 1-2 mm Dot Activity  200 Bq 50 cm total wire length Reference Mark 20.0 cm distance between Mark and Dot Central Am Dot WIRE SOURCES FOR PISA DEVICE 2 WIRES, 1 DOT-SOURCE PER WIRE

18. 18 February 9th 2005

19. 19 rather narrow energy-spectra possible mounting on special supports and screws

20. 20 February 9th 2005 Will it be possible to use them @ beam on?

21. 21 February 9th 2005 2) 9 MeV gamma line from neutron capture on NickelExperimental set-up 2) 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.

22. 22 February 9th 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 2 2.2 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

23. 23 February 9th 2005 9 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 in April, with Am/Be source) D + 2 H  3 He + n Q = 3.27 MeV D + 3 H  4 He + n Q = 17.59 MeV Polyethylene 0.25 cm Nickel plate 3 cm 20 cm

24. 24 February 9th 2005 Possibilities POLY Am/Be 0.25 cm Nickel n POLY 3 cm polyethylene NaI

25. 25 February 9th 2005 3)  0 calibration… Target Anti Counter up tilt down Support structure: straightly up and down Tilt mechanism at every height for NaI front to face target direction. target 0000   Proton beam: 1.8mA Pion Rate: 2x10 7  - /sec Collimate: 2PMTs x 2PMTs ~ 150cm 2 (1 position) 2  /sec # of PMTs on incident face: 216 PMTs (54 positions) required: 30,000 evts/position takes 30,000 x 54 / 2 = 810,000sec~ 10 days How often can it be performed?

26. 26 February 9th 2005 3) Further calibration methods... 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. 21 1 (1960), Zeitschrift f. Physik A351 229 (1995)] 3 7 Li (p,  ) 4 8 Be

27. 27 February 9th 2005 Previously used...

28. 28 February 9th 2005 3 7 Li (p,  ) 4 8 Be resonant at E p = 440 keV  =14 keV  peak = 5 mb E  0 = 17.6 MeV E  1 = 14.6 6.1 B peak  0 /(  0+  1 )= 0.72  0.07 NaI 12”x12”  spectrum 11 00 Crystal Ball Data

29. 29 February 9th 2005 5 11 B (p,  ) 6 12 C lower proton energy ! lower rate at 50  A !! A further interesting possibility... Cecil et al. NP A539 75 (1992) 10x10 cm NaI crystal resonant at E p = 163 keV  = 7 keV E  0 = 16.1 MeV  peak = 5.5  b E  1 = 11.7 + 4.4  peak = 152  b  750  0 /s (isotropic)  20.000  1 /s for I p  50  A

30. 30 February 9th 2005 NOW: GLAST SPACE EXPERIMENT CRYSTAL CALORIMETER CALIBRATION It is the old VDG of the Crystal Box experiment ! ! they have some problems: old device, max. VDG p-energy is 400 KeV out of resonance:  -rate reduced by factor  5000 How can we get one such device ?? We are exploring several possibilities... 180 cm target-pipe

31. 31 February 9th 2005 rails cockroft focusing elements (magnetic or electrostatic ?) Cal. calibration from the target position, monitoring at the cal. back at the cal. back the proton motion in the COBRA field must be be studied

32. 32 February 9th 2005 proton MC trajectories E p  440 keV   28 MeV/c !! Z(cm) X(cm) Y(cm) the protons are not reflected back by the varying magnetic field Θ ~ 8   giroradius < 12 cm

33. 33 February 9th 2005 Z(cm) X(cm) Y(cm) ρ ~0.8cm Plane Z = 0 cm Θ ~ 0.5   giroradius < 1 cm

34. 34 February 9th 2005 KEEP MEG UNDER CONTROL PARTICULARLY AT HIGH (AND VARIABLE) BEAM INTENSITIES......... frequent checks of calorimeter energy scale, linearity and stability checks of LXe optical properties energy resolution and spacial resolution shower properties at the right  energy (  53 MeV), but also at other energies..... no single calibration method has all the required characteristics use complementary (and redundant) methods, make the best use of their intrinsic properties emphasize the reliability of our experiment BR   e  ~10 -13 Beam Intensity~5 10 7  /s

35. 35 February 9th 2005 5) PMT tests = 50 pC F18, TB typeF0, 6041 (old) = 87 pC PMT in LP, LED pulsed (@ 1 khz)

36. 36 February 9th 2005 10 Khz = 50 pC TB 6041 = 87 pC photocathode saturation effect

37. 37 February 9th 2005 50 Khz = 50 pC TB 6041 = 87 pC photocathode saturation effect

38. 38 February 9th 2005 100 Khz = 50 pC TB 6041 = 87 pC Gain non linearity

39. 39 February 9th 2005 6041  = 115 s Anode current should be < 0.5  A

40. 40 February 9th 2005 TB Lower photocathode resistivity (ZA much better)

41. 41 February 9th 2005 Zener Diodes on PMT Base

42. 42 Linearity much improved presently installed PMT with Zener T=-108ºC

43. 43 But … Zener problem at low temperature 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

44. 44 Several Zener diode types tried SellerBrandPackage DistrelecFairChildGlass FarnellPhillipsplastic RS On semicond plastic RSPhillipsCeramic Original...plastic RSVishaysinter gl.

45. 45 Results: FairChild 68+755 Hz 75+75200 Hz (75//75)x23 Hz

46. 46 February 9th 2005 R9288 base with low pass filter Optimum resistance will be something around 100KOhm Low pass filter is built in by adding resistors serial to Zener If the resistance is too small, filtering will not work. With too large resistance, the effect of Zener will be little under high rate BG environment

47. 47 February 9th 2005 Low pass filter in PMT base @ Astro-E2 HXD PMT base with Zener diode and low pass filter is adopted in Astro-E2 Hard X-ray Detector. (HXD) Fifth Japanese space X-ray observatory PMT+BGO High counting rate HXD will be cooled downed to –30 °C Zener is used in this base circuit and low pass filter is built in because of the noise from Zener. Various tests have been performed with this base and its good performance was confirmed so far.

48. 48 February 9th 2005 PMT Test using the base with Low Pass filter Type ZType ZR

49. 49 February 9th 2005 Chamber Set Up Type ZR Gas xenon Alpha source LED Type Z Upper PMT temp. ~ - 85 °C Lower PMT temp. ~ - 100 °C HV=800V for both PMTs Same interstage volt., same current between 2 PMTs

50. 50 February 9th 2005 Oscilloscope Snapshot Type Z Type ZR Yasuko HISAMATSUMEG Collaboration Meeting Feb. 2005 No noise was observed!! Noise from Zener Alpha event

51. 51 February 9th 2005  We have an alternative; active base with MOS-FET  Adopted in the πβ experiment  MOS-FET is operational in 165K If the base Type ZR doesn’t work…

52. 52 February 9th 2005 When a solution is found Start testing PMTs: 300-400 at Pisa (Cryo facility) and 600-700 at PSI (LP)

53. 53 February 9th 2005 6) Cryostat: designs ready; tenders and procurements organization Tenders have been organized in three parts: 1.Conventional part 2.Cold and warm windows 3.Purchasing of the cold sealing 4.PMTs supporting structure 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.

54. 54 February 9th 2005 SIMIC profile in cryogenics application http://www.simic.it/eng/home.htm

55. 55 February 9th 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)

56. 56 February 9th 2005 FEA studies are in progress

57. 57 February 9th 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

58. 58 February 9th 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

59. 59 February 9th 2005 Cold joints: interaction with the factory Modification of bolts position and number We asked non-magnetic seal

60. 60 February 9th 2005 Pisa 30-December-2004 Cold joints

61. 61 February 9th 2005 PMTs supporting structure design

62. 62 February 9th 2005 Some issues recently reviewed Detailed drawings of internal attachments Windows area dimensions reviewed. Superinsulation required to the company Electro polishing of internal surfaces Outer vessel isolated from the base. (A G10 plate will be placed under the cryostat legs) Reviewed the height of all components Metallic o-rings to be fixed in the vertical position Guiding pins needs to be added on the cold and on the warm flange to avoiding that the studs are hitting the contact surface of the o-ring on the covers

63. 63 February 9th 2005 Calorimeter schedule 2005

64. 64 February 9th 2005 Neutron measurements status 4