1 A, Baldini, Pisa 10 maggio 2005 Richieste per l’esperimento MEG (in costruzione) a)Timing counter: illustrazione dello stato attuale: richieste sblocchi s.j. per Genova e di sblocco + ulteriore assegnazione per Pavia b)Calorimetro a Xenon liquido. Breve stato della PMT test facility. Richiesta di contributo all’acquisto di un acc. CW per la calibrazione (piccola richiesta di sblocco s.j. M.E. per Lecce)

2 A, Baldini, Pisa 10 maggio 2005 a) TC: TC Final Design A PLASTIC (BLACK PLEXIGLASS) SUPPORT STRUCTURE ARRANGES THE SCINTILLATOR BARS AS REQUESTED THE BARS ARE GLUED ONTO THE SUPPORT “LIGHT” INTERFACE ELEMENTS ARE GLUED ONTO THE BARS AND SUPPORT THE FIBRES FIBRES ARE GLUED AS WELL TEMPORARY ALUMINIUM BEAMS ARE USED TO HANDLE THE DETECTOR DURING INSTALLATION PTFE SLIDERS WILL ENSURE A SMOOTH MOTION ALONG THE RAILS

3 A, Baldini, Pisa 10 maggio 2005 TC final design (PMTs interface to scintillators) PMTs ARE ATTACHED, BY MEANS OF THE INTERFACE SOCKET, TO THESCINTILLATOR BARS GIVEN THE MASS, AN ELASTIC AND REMOVABLE SILICONE GLUE IS APPROPRIATE THE HOLLOW INTERFACE ELEMENT IS A “CUSTOMDESIGNED” PROFILE THAT ADDS A MINIMUM AMOUNT OF MATERIAL BETWEEN THE FIBRES AND THE BARS SLOT FOR CABLES and OPTICAL FIBERS HAVE BEEN FORESEEN TO ALLOW THE CABLES FROM THE INNER PMT TO EXIT

4 A, Baldini, Pisa 10 maggio 2005 Construction status Under construction BC 404 scintillator bars PMT sockets Scint. Fiber adapter To be define soon Definition of the supporting structure and construction (july) Insert APD read-out system in the final design (july) APD amplifier PCB and production (end of sept.) Validation test at BTF of 10 elements of curved detectors-june (we are undertaking a preliminary test with cosmics) Final construction of whole TC (sept-nov). Estimate delivery of the timing counter end of november BTF: december Under study (advance status) TC bag TC curved detector pattern generator TC linear detector DRS matching electronics

5 A, Baldini, Pisa 10 maggio 2005 APD intercalati con passo di 5mm Vista lato frontale APD, sezione per la lettura di 10 fibre scintillanti Vista sezione trasversale con, fibre, elettronica, cooling.

6 A, Baldini, Pisa 10 maggio 2005 TC bag inside cobra prototype design under study. Plastics considered: EVOH, SARAN, FEP, Nylon 6, TEP Polyamide

7 A, Baldini, Pisa 10 maggio 2005 TC curved (trigger & pattern): APD test system Pulsed Laser Integrating Calibrated Photometer Fast Photodiode Photomult iplier 1/1000 attenuator Splitters APD Copper block Peltier Cell

8 A, Baldini, Pisa 10 maggio 2005 Test of the CMS APDs (90% acceptance)

9 A, Baldini, Pisa 10 maggio 2005 Richieste Ge: sblocco di 2 K€ (inv.) + 32 K€ (app.) + 15 K€ (consumo) per elettronica e meccanica sistema APD Pv: 21 K€ (app.) per sistema di test PMT contatore long. 20 K€ (app.) per realizzazione sistema di misura a doppisa soglia di discriminazione (utilizzabili 20K€ s.j. per RGA) sblocco 10 K€ M.E. S.j. Le: Sblocco 10 K€ M.E: s.j.

10 A, Baldini, Pisa 10 maggio 2005 b) LXe calorimeter: Pisa PMT test facility Solution to the Zener noise problem OK First 30 PMTs received at pisa on may 6th PMT testing (3-4/day)

11 A, Baldini, Pisa 10 maggio 2005 QE systematics

12 A, Baldini, Pisa 10 maggio 2005 Purity dependence Despite the overall determination within 5% there are systematic dependences Amplitude dependence Purity dependence – can be explained with different distance from source gain corrected

13 A, Baldini, Pisa 10 maggio 2005 Nota interna MEG (MEG-TN027) per la CSN1 Metodi di calibrazione e monitor per il calorimetro di MEG e per tutto l’esperimento

14 A, Baldini, Pisa 10 maggio 2005 Il controllo del calorimetro e.m. di MEG a rate di decadimento elevati e variabili 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  ~ Beam Intensity~  /s richiede

15 A, Baldini, Pisa 10 maggio 2005 Wire presently mounted in “Large Prototype” 1) Am SOURCES ON WIRE AND WALLS Potentialities : PMT quantum efficiencies Xenon optical properties low-energy position and energy calibration use in Xe gas and liquid stability checks ? a unique method for cryogenic liquid detectors !! Sources in production. Soon available for all LXe devices. Open problems: will the method be usable under full intensity beam conditions ? To be verified by test !

16 A, Baldini, Pisa 10 maggio 2005 reconstruction of the 8  -source positions in gaseous Xe. Recent measurement with the large-prototype. (Po-source produced in Genoa)

17 A, Baldini, Pisa 10 maggio 2005 RINGS IN LIQUID XENON the ring radius has some dependence on the Rayleigh scattering length in LXe  -range (2  m) and wire shadow (  100  m) reflection on Al

18 A, Baldini, Pisa 10 maggio 2005 Determination of the relative QE for 4 different PMTs of the large-prototype by the use of 4 dot-wire-sources in Xe gas the relative QEs are given by the slope of the linear fits.

19 A, Baldini, Pisa 10 maggio 2005

20 MEG internal note e poi NIM collaboration paper

21 A, Baldini, Pisa 10 maggio MeV Nickel γ-line NaI 20 x 20 x 36 cm 3 neutron generator 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 2)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  e5 beam on Tg-on Tg-off

22 A, Baldini, Pisa 10 maggio 2005 large-prototype in the large-prototype the line is worse..... the measurement must be repeated, protecting LXe from thermal neutrons by a Boron-foil NaI  /E=2.5%  9 /(generated neutron)  2x10 -3

23 A, Baldini, Pisa 10 maggio 2005  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  0 Rate:  10 6  0 /sec Collimate: 2PMTs x 2PMTs ~ 150cm 2 (1 position) 1  /sec # of PMTs on incident face: 216 PMTs (54 positions) required: 10,000 evts/position takes 10,000 x 54=540,000 s ~ 6 d + time for movements !! How often can it be performed?

24 A, Baldini, Pisa 10 maggio 2005 an interesting possibility to speed-up the  calibration abandon collimators and NaI detector in coincidence illuminate the whole calorimeter at the same time with  -1 convert the  -2 in a 0.1 X 0 converter close to the H 2 target detect conversion and measure conversion point with a Si-detector measure e + branch of the pair in the chambers use part of the information for selecting  - 2 by trigger angle between  ’ s defined by impact points on LXe-Cal and Si-detector (angles  useful for calibrating at different energies) loss at conversion but huge increase in solid angle MC METHOD SIMULATION RESULTS A FULL TEST OF THE WIRE CHAMBERS CAN ALSO BE PERFORMED !

25 A, Baldini, Pisa 10 maggio 2005 Un evento Photon Positron Electron Hydrogen target + Tungsten converter

26 A, Baldini, Pisa 10 maggio 2005 Rough estimate of the time needed for the LXe calibration   (20  30)/10 5 /10 = (20  30) x  R = R  0 x = (R  0 /10 6 ) x 10 6 x (20  30) x = (20  30) x (R  0 /10 6 ) Hz (R  0 /10 6 ) x 10 6 x (20  30) x = (20  30) x (R  0 /10 6 ) Hz  Events/day  8.64 x 10 4 R  2 x 10 6 x (R  0 /10 6 )  Assuming  50 locations to be calibrated (216 PMTs in groups of 4): (216 PMTs in groups of 4): Events/day/location  4 x 10 4 x (R  0 /10 6 ) Events/day/location  4 x 10 4 x (R  0 /10 6 ) largely sufficient.... largely sufficient.... Solid angle factor

27 A, Baldini, Pisa 10 maggio 2005 but also the Cockroft-Walton allows a calibration of the LXe Cal and of the wire-chambers CW use is much simpler than  calibration ! LXe Cal illuminated by 17.6 MeV  ’s at high rate Use of  -converter for testing the wire-chambers but maximum COBRA field for LXe Cal test half COBRA field for wire-chamber test WIRE CHAMBERS TEST (at full COBRA field) by  - p   0 n and  - 2 conversion into an e + e – pair and also by  - p  n  and  conversion into an e + e – pair

28 A, Baldini, Pisa 10 maggio ) 500 KV PROTON ACCELERATOR AND LITIUM TARGET FOR A 17.6 MEV GAMMA LINE Potentialities : a unique nuclear reaction with a high energy  -line obtainable : at resonance (E p = 440 keV  14 keV)  10 6  /s (isotropic) for 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. monitoring at the back of the calorimeter possibly front: rather frequent use, back: frequent use Open problems: compatibility with normal beam and target ? COBRA field, accelerator and focusing element positions project for easiness of target-tube mounting p-beam divergence and protons on target; p  29 MeV/c post-acceleration to scan the resonance [P.R. 73, 666 (1948), N.P (1960), Zeitschrift f. Physik A (1995)] 3 7 Li (p,  ) 4 8 Be

29 A, Baldini, Pisa 10 maggio Li (p,  ) 4 8 Be resonant at E p = 440 keV  =14 keV  peak = 5 mb E  0 = 17.6 MeV E  1 = B peak  0 /(  0+  1 )= 0.72  0.07 NaI 12”x12”  spectrum 11 00 Crystal Ball Data

30 A, Baldini, Pisa 10 maggio B (p,  ) 6 12 C lower proton energy ! lower rate at 50  A !! another interesting possibility Cecil et al. NP A (1992) 10x10 cm NaI crystal resonant at E p = 163 keV  = 7 keV E  0 = 16.1 MeV  peak = 5.5  b E  1 =  peak = 152  b  750  0 /s (isotropic)   1 /s for I p  50  A

31 A, Baldini, Pisa 10 maggio 2005 the High Voltage Engineering 0.5 MeV Cockroft & Walton model: “coaxial SINGLETRON” with H + plasma source

32 A, Baldini, Pisa 10 maggio 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 studied

33 A, Baldini, Pisa 10 maggio 2005 Z(cm) X(cm) Y(cm) ρ ~0.8cm Plane Z = 0 cm Θ ~ 0.5   giroradius < 1 cm (Θ ~ 8   giroradius < 12 cm) proton MC trajectories E p  440 keV   28 MeV/c !! the protons are not reflected back by the varying magnetic field

34 A, Baldini, Pisa 10 maggio 2005 The old Van der Graaf of the previous  e  experiment generates an e + e – pair, at 17.6 MeV, seen in the GLAST calorimeter

35 A, Baldini, Pisa 10 maggio 2005 RADIO FREQUENCY QUADRUPOLE ACCELERATOR practically monoenergetic pulsed operation; frequency 100 Hz 100  s pulses average current 50  A, pulsed current 5 mA beam energy bin approx. 50 keV small vessel beam optical properties ? 1mm ; 20 mR RF radiation ? No proton source ? Plasma cost ? !!!!! special design....time to produce ? One year not an out-of-the-shelf machine Companies: AccSys, Neue Technologien GMBH

36 A, Baldini, Pisa 10 maggio 2005

37 attempt to grade the different C&M methods

38 A, Baldini, Pisa 10 maggio 2005 Conclusioni e richieste sulle calibrazioni Monitorare frequentemente la risoluzione in energia di fotoni (E >15 MeV) entranti dalla faccia frontale e’ l’unico modo diretto per tenere sotto controllo il fondo accidentale Il metodo del  0 non puo’ essere usato se non una volta ogni qualche (6 –12 ?) mese perche’ si prevede una durata di questo calibrazione per circa due settimane. Con il CW si puo’ pensare ad una calibrazione (forse) giornaliera. Il CW consentirebbe un ulteriore numero di possibili calibrazioni e il miglior utilizzo del tempo fascio Costo: 500 K€. Proposta di sharing al 50% con un gruppo di UCI (Bill Molzon)

39 A, Baldini, Pisa 10 maggio 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

40 A, Baldini, Pisa 10 maggio 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€ Assegnato1602 K€ Previsto finale1992 K€ Risparmio 208 K€ Stime di costo aggiornate Previsioni Assegnazioni Risparmi Non previsti: Software 22 K€ Calibrazioni 50 K€ PMT 170 K€ 242 K€

41 A, Baldini, Pisa 10 maggio 2005 Budget (K€) +700 (400 PMT) +500 (aumento costo Xenon: non previsto)