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

A, Baldini, Roma 1 Febbraio 200511

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 !Presentazione al contrario !: 1) timing : 1) timing counter, 2)calibrazioni, 3) trigger, 4) counter, 2)calibrazioni, 3) trigger, 4)

criostato, 5) PMTcriostato, 5) PMT


1) Timing counter: beam test Frascati

(nov 04) Beam focusx=2.5 mmy= 3.0 mm

5 mm Beam Geom. Select 2-electron veto


Risoluzione temporale misurata

Timing resolution of BC 404

70

75

80

85

90

95

100

105

-40 -30 -20 -10 0 10 20 30 40

distanc e from c enter (c m)

D

90 deg

65 deg

53 deg

40 deg

Goal


Validation test in COBRA (dec 04)

19.5º 21.5

From COBRA center

105 cm 25 cm

BB

Pulsed Laser

Pulsed Laser

101 ps

98 ps


Prototipo per la misura del tempo con discriminazione a due soglie

DHDH

HLTh

DLDL

& &

DLY

LLTh

S_In

1

2

3

4

Realizzazione di un modulo di elettronica NIM a 8 canali


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.

77

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 face Lateral face


•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

1010

Small displacement of the two front wires

LXe GXe

1111

PMT alpha direction

1212

Charge vs Cos in LXeFront Face

Data MC

1313

LXe/MC

New PMTs

Old PMTs4 front sources

1414

LXe/MC

After applying QEs

4 front sources

1515

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

1616

Po half-life=138 days

Trigger was changed several times …


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, Pragueworking 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 DETECTORSunique feature !


Wire of 100 micron diameterMaterial: gold plated steel or tungsten Total length 150 cmSpacing of dot-sources 12.4 cmLinear dimension of dots 1-2 mmActivity 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 CALORIMETER15 WIRES, 5 DOT-SOURCES PER WIRE


rather narrowenergy-spectra

possible mounting on special

supports and screws


b) 9 MeV gamma line from neutron capture b) 9 MeV gamma line from neutron capture on Nickelon Nickel:Experimental set-upExperimental set-up

- Am-Be source Am-Be source (20000 n/s);(20000 n/s);

- Polyethylene;Polyethylene;

- Nickel platesNickel plates 30 x 30 cm30 x 30 cm22 ((0.5 cm0.5 cm and and 0.25 cm0.25 cm thickness)thickness) - 20 x 20 x 36 cm20 x 20 x 36 cm33 NaI detectorNaI detector

-MCAMCA ORTECORTEC (2048 channels)(2048 channels)

- NIM electronics.NIM electronics.


γ-line from n-capture on Ni, I, Al, H2; natural radioactivity Tl, K; Am/Be source

Am/Be4.4 MeV &1st escape

I6.8 Mev

Al7.7 MeV

Ni9 MeV

Ni8.54 MeV &1st escape

H2

2.2 MeV

Tl2.6 MeV

Black: Am/Be source and 1 cm Ni Red: no Am/Be sourceGreen: no Am-Be source, no Ni(Gotta Beam on)

K1.46 MeV


9 MeV Nickel γ-line

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

neutron generator (Pavia ?)

• 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

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


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


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 : 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; p29 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

7Li (p,)48Be


1982 !!

PREVIOUS e EXPERIMENT


NOW: GLAST SPACE EXPERIMENTCRYSTAL CALORIMETER CALIBRATION

It is the old VDG of the Crystal Ball experiment ! !they have some problems: old device, max. VDG p-energy is 400 KeVout 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


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


4) Cryostat: designs ready; tenders and procurements organization

Tenders have been organized in three parts:1. Conventional part2. 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 10th month.

Totale offerte e stima circa 160 K€

Finanziato nel 2004 (200 K€)


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)


FEA studies are in progress

0

0,00005

0,0001

0,00015

0,0002

0,00025

0,0003

0,00035

0,0004

0,00045

0,0005

0,0003 0,0004 0,0006 0,001

thickness ( m )

max

dis

plac

emen

t ( m

)

incastro max displ-thickness cerniera max displ-thickness

0

20000000

40000000

60000000

80000000

100000000

120000000

140000000

160000000

180000000

200000000

0,0003 0,0004 0,0006 0,001

thickness ( m )

max

prin

cipa

l ( P

a )

cerniera max princ-thickness membrane theory

0

20000000

40000000

60000000

80000000

100000000

120000000

140000000

160000000

180000000

200000000

0,0003 0,0004 0,0006 0,001

thickness ( m )

max

prin

cipa

l ( P

a )

Incastro max princ-thickness membrane theory


Honeycomb structure discussed with manufacturing company

Internal welded foil .3 mm or less welded on externalFrame necessary to test the window prior the final welding on the cryostat body.

Bolted area

This area is reinforced

Honeycomb structureTwo facing of .7 mm CFRP.(intermediate high module CF withEpoxy space approved)Core aluminum honeycombperforated


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


Cold joints: interaction with the factory

Modification of bolts position and number

We asked a seal no-magnetic


Pisa 30-December-2004Cold joints


Struttura di supporto dei PMT: disegno pronto


1st generation R6041Q 2nd generation R9288TB 3rd 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.

1st compact version

QE~4-6%

Under high rate background,

PMT output reduced by 10

-20% 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


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€)


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 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€

• Meccanica 60 K€

Risparmio totale -225K€

(rispetto ai 700 K€)

Splitters

• Sistema completo 115 K€

+15 K€

TOTALE MoU 2200 K€

Assegnato 1155 K€

Previsto finale 1750 K€

Risparmio 450 K€

Stime di costo aggiornatePrevisioni Assegnazioni Risparmi

Non previsti:

Software 22.5 K€

Calibrazioni 50 K€

PMT 170 K€

242.5 K€


Fine

4141

Zener diodes in the last two ampl. stages of the base

presently installed

PMT with Zener

T=-108ºC

4242

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

4343

Several Zener diode types tried

Seller Brand Package

Distrelec FairChild Glass

Farnell Phillips plastic

RS On semicond plastic

RS Phillips Ceramic

Original ... plastic

RS Vishay sinter gl.

4444

Results: FairChild

68+75 5 Hz

75+75 200 Hz

(75//75)x2 3 Hz


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 ?

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

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