stato dell’esperimento meg e richieste di sblocco s.j
DESCRIPTION
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.) - PowerPoint PPT PresentationTRANSCRIPT
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
A, Baldini, Roma 1 Febbraio 200522
1) Timing counter: beam test Frascati
(nov 04) Beam focusx=2.5 mmy= 3.0 mm
5 mm Beam Geom. Select 2-electron veto
A, Baldini, Roma 1 Febbraio 200533
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
A, Baldini, Roma 1 Febbraio 200544
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
A, Baldini, Roma 1 Febbraio 200555
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
A, Baldini, Roma 1 Febbraio 200566
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
88
A, Baldini, Roma 1 Febbraio 200599
•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 …
A, Baldini, Roma 1 Febbraio 20051717
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 !
A, Baldini, Roma 1 Febbraio 20051818
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
A, Baldini, Roma 1 Febbraio 20051919
rather narrowenergy-spectra
possible mounting on special
supports and screws
A, Baldini, Roma 1 Febbraio 20052020
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.
A, Baldini, Roma 1 Febbraio 20052121
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
A, Baldini, Roma 1 Febbraio 20052222
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
A, Baldini, Roma 1 Febbraio 20052323
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
A, Baldini, Roma 1 Febbraio 20052424
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
A, Baldini, Roma 1 Febbraio 20052525
1982 !!
PREVIOUS e EXPERIMENT
A, Baldini, Roma 1 Febbraio 20052626
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
A, Baldini, Roma 1 Febbraio 20052727
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
A, Baldini, Roma 1 Febbraio 20052828
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€)
A, Baldini, Roma 1 Febbraio 20052929
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)
A, Baldini, Roma 1 Febbraio 20053030
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
A, Baldini, Roma 1 Febbraio 20053131
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
A, Baldini, Roma 1 Febbraio 20053232
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
A, Baldini, Roma 1 Febbraio 20053333
Cold joints: interaction with the factory
Modification of bolts position and number
We asked a seal no-magnetic
A, Baldini, Roma 1 Febbraio 20053434
Pisa 30-December-2004Cold joints
A, Baldini, Roma 1 Febbraio 20053535
Struttura di supporto dei PMT: disegno pronto
A, Baldini, Roma 1 Febbraio 20053636
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
A, Baldini, Roma 1 Febbraio 20053737
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€)
A, Baldini, Roma 1 Febbraio 20053838
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
A, Baldini, Roma 1 Febbraio 20053939
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€
A, Baldini, Roma 1 Febbraio 20054040
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
A, Baldini, Roma 1 Febbraio 20054545
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 ?