Richieste per l’esperimento MEG (in costruzione)

A, Baldini, Pisa 10 maggio 200511

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)


a) TC: TC Final Design• A PLASTIC (BLACK PLEXIGLASS) SUPPORT STRUCTURE ARRANGES THESCINTILLATOR BARS AS REQUESTED

• THE BARS ARE GLUED ONTOTHE SUPPORT

• “LIGHT” INTERFACE ELEMENTS ARE GLUED ONTO THE BARS AND SUPPORT THEFIBRES

• FIBRES ARE GLUED AS WELL

• TEMPORARY ALUMINIUM BEAMS ARE USED TO HANDLE THE DETECTOR DURINGINSTALLATION

• PTFE SLIDERS WILL ENSUREA SMOOTH MOTION ALONG THE RAILS


TC final design (PMTs interface to scintillators)

• PMTs ARE ATTACHED, BYMEANS OF THE INTERFACE SOCKET, TO THESCINTILLATOR BARS

• GIVEN THE MASS, AN ELASTIC AND REMOVABLE SILICONE GLUE ISAPPROPRIATE

• THE HOLLOW INTERFACEELEMENT IS A “CUSTOMDESIGNED”PROFILE THAT ADDS A MINIMUM AMOUNT OF MATERIAL BETWEENTHE FIBRES AND THE BARS

• SLOT FOR CABLES and OPTICAL FIBERS HAVE BEEN FORESEEN TOALLOW THE CABLES FROM THE INNER PMT TO EXIT


Construction statusUnder 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• Test @ BTF: december

Under study (advance status)• TC bag• TC curved detector pattern generator• TC linear detector DRS matching electronics


Peltier Cell

Copper Cold Finger(~20°)

Scint. Fibers

Black Coating

APD

Heat Exchanger

Electronics boards -10 channels

Transition board

Kapton Flex.

APD intercalati con passo di 5mm

Vista lato frontaleAPD, sezione per la lettura di 10 fibre scintillanti

Vista sezione trasversale con, fibre, elettronica,cooling.


TC bag inside cobra prototype design under study. Plastics considered: EVOH,

SARAN, FEP, Nylon 6, TEP Polyamide


TC curved (trigger & pattern):

APD test system

Pulsed Laser

Integrating CalibratedPhotometer

Fast Photodiode

Photomultiplier

1/1000 attenuator

Splitters

APDCopper block

Peltier Cell


Test of the CMS APDs (90% acceptance)

I dark vs H.V. Temperature 20°C

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

2.50E+02 3.00E+02 3.50E+02 4.00E+02 4.50E+02 5.00E+02

H.V. (Volts)

I Dar

k @

10M

ohm

(Vol

ts)

APD0210117506_20ID_MAPD0107115426_20ID_MAPD8411087442_20ID_MAPD8418088162_20ID_MAPD8223084713_20ID_MAPD8201082393_20ID_MAPD1910145247_20ID_MAPD8024081013_20ID_MAPD8007079173_20ID_MAPD791478311_20ID_MAPD1908145087_20ID_MAPD1905144927_20ID_MAPD1906145007_20ID_MAPD1909145167_20ID_MAPD1913145407_20ID_MAPD1902144767_20ID_MAPD1903144847_20ID_MAPD1911145327_20ID_MAPD8206082873_20ID_MAPD1222134415_20ID_MAPD1212133615_20ID_MAPD1211133535_20ID_MAPD1213133695_20ID_MAPD1218134175_20ID_MAPD8710092535_20ID_MAPD8810094569_20ID_MAPD8822095449_20ID_MAPD8709092455_20ID_MAPD8722093575_20ID_MAPD8711092615_20ID_MAPD8811094649_20ID_MAPD8619091391_20ID_MAPD8601089791_20ID_MAPD1512138823_20ID_MAPD1511138743_20ID_MAPD1822144554_20ID_MAPD1812143994_20ID_MAPD1704141813_20ID_MAPD1720142933_20ID_MAPD1613140756_20ID_MAPD1611140596_20ID_MAPD1612140676_20ID_MAPD1616140996_20ID_MAPDJA0296_20ID_MAPDJA0302_20ID_MAPDJA0288_20ID_MAPDJA0307_20ID_MAPDJA0312_20ID_MAPDJA0308_20ID_MAPDJA0309_20ID_MAPDJA0311_20ID_MAPDJA0295_20ID_MAPDJA0289_20ID_MAPDJa0290_20ID_MAPDJA0292_20ID_MAPDJA0294_20ID_MAPDJA0316_20ID_MAPDJA0304_20ID_MAPDJA0305_20ID_M


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.


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)


QE systematics


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


Nota interna MEG (MEG-TN027) per la CSN1

Metodi di calibrazione e monitor per il calorimetro di MEG e per tutto l’esperimento


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 characteristicsuse complementary (and redundant) methods,

make the best use of their intrinsic properties emphasize the reliability of our experiment !

BR e ~10-13 Beam Intensity~5 107 /s

richiede


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 !


reconstruction of the 8 -source positions in gaseous Xe. Recent measurement with the large-prototype.

(Po-source produced in Genoa)


RINGS IN

LIQUID XENON

the ring radiushas some dependence on

the Rayleigh scattering lengthin LXe

-range (2m) andwire shadow (100 m)

reflection on Al


Determination of the relative QE for 4 different PMTs of the large-prototype bythe use of 4 dot-wire-sourcesin Xe gas

the relative QEs are given by the slope of the linear fits.


MEG internal note e poi NIM collaboration paper


9 MeV Nickel γ-line

NaI 20 x 20 x 36 cmNaI 20 x 20 x 36 cm33

neutron generator

• 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

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 + 2H 3He + n Q = 3.27 MeV

D + 3H 4He + n Q = 17.59 MeV

Polyethylene

0.25 cm Nickel plate3 cm 20 cm

e5 beam onTg-on

Tg-off


large-prototype

in the large-prototypethe line is worse.....the measurement must berepeated, protecting LXe fromthermal neutrons by a Boron-foil

NaI

/E=2.5%

9 /(generated neutron)2x10-3


0 calibration…

Target

Anti Counter

up

tilt

down

Support structure: straightly up and downTilt mechanism at every height for NaI front to face target direction.

target

00

• Proton beam: 1.8mA• 0 Rate: 106 0/sec• Collimate: 2PMTs x 2PMTs ~ 150cm2

(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 How often can it be performed?performed?


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 X0 converter close to the H2 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 1800 useful for calibrating at different energies)

loss at conversion but huge increase in solid angle

MC METHOD SIMULATION RESULTSA FULL TEST OF THE WIRE CHAMBERS

CAN ALSO BE PERFORMED !


Un evento

PhotonPhoton PositronPositron

ElectronElectronHydrogen target Hydrogen target + Tungsten converter+ Tungsten converter


Rough estimate of the time needed for the LXe

calibration <<>> (20 (20 30)/10 30)/1055/10 = /10 = (20 (20 30) x 10 30) x 10-6-6 RR = R = R00 x < x <> = > = (R(R00/10/1066)) x 10x 1066 x (20 x (20 30) x 10 30) x 10-6-6 = = (20 (20 30) x (R 30) x (R00/10/1066) Hz) Hz Events/dayEvents/day 8.64 x 10 8.64 x 1044 R R 2 x 102 x 1066 x (R x (R00/10/1066)) Assuming Assuming 50 locations50 locations to be calibrated to be calibrated (216 PMTs in groups of 4): (216 PMTs in groups of 4):

Events/day/location Events/day/location 4 x 10 4 x 1044 x (R x (R00/10/1066)) largely sufficient....largely sufficient....

Solid angle factorSolid angle factor


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–

pairand also

by - p n and conversion into an e+ e– pair


4) 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) 106 /s (isotropic) for 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.• 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; p29 MeV/c • post-acceleration to scan the resonance

[P.R. 73, 666 (1948), N.P. 21 1 (1960), Zeitschrift f. Physik A351 229 (1995)] 3

7Li (p,)48Be


37Li (p,)4

8Be

resonant at Ep= 440 keV =14 keV peak = 5 mbE0 = 17.6 MeVE1 = 14.6 6.1Bpeak 0/(0+ 1)= 0.720.07

NaI 12”x12” spectrum

1

0

Crystal Ball Data


511B (p,)6

12C

lower proton energy !lower rate at 50 A !!

another interesting possibility...... Cecil et al. NP A539 75 (1992)10x10 cm NaI crystal

resonant at Ep= 163 keV= 7 keVE0 = 16.1 MeV peak = 5.5 bE1 = 11.7 + 4.4 peak = 152 b

750 0/s (isotropic) 20.000 1/s for Ip 50 A


the High Voltage Engineering0.5 MeV Cockroft & Walton

model: “coaxial SINGLETRON”

with H+ plasma source


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


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 trajectoriesEp 440 keV 28 MeV/c !!

the protons are not reflected back by the varying magnetic field


The old Van der Graaf of the previous e experiment .......generates an e+ e– pair, at 17.6 MeV, seen in the GLAST calorimeter


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


attempt to grade the different C&M methods


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)

2E


Dal MoU di MEG

Appendix 1. INFN contribution to the different subdetectors

Item Cost (K€)

LXe cryostat 400

PMTs test and purchase

600

Timing counter

700

Splitters 100

Trigger 400

Total 2200


LXenon• PMT 500 K€ -100K€• Criostato 200 K€ (criostato)

160 K€ (supporto + finestre) -40K€

Trigger• Prototipi 40 K€• Sistema completo 145+115 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€• Meccanica 60 K€Risparmio totale -225K€(rispetto ai 700 K€)

Splitters• Sistema completo 115 K€

+15 K€

TOTALE MoU 2200 K€Assegnato 1602 K€Previsto finale 1992 K€Risparmio 208 K€

Stime di costo aggiornatePrevisioni Assegnazioni Risparmi

Non previsti:• Software 22 K€

• Calibrazioni 50 K€

• PMT 170 K€

242 K€


Budget (K€)Calorimeter PMT 1756Lxe 845Vessel 400Various items 271Xe system 369Cobra Magnet 1175

Timing counter 700Trigger 400

Drift Chambers 149Muon transport 184DAQ Electronics 405Detectors environment 172HV 39

6865

Japan 2529Italy 2200PSI 1299

6028

Running costs - 2008 1303

+700 (400 PMT)

+500 (aumento costo Xenon: non previsto)

Richieste per l’esperimento MEG (in costruzione)

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