baldini

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 !: 1) timing counter,
2)calibrazioni, 3) trigger, 4) criostato, 5) PMT
A, Baldini, Roma 1 Febbraio 2005
1
1) Timing counter: beam
test Frascati (nov 04)
Beam focus
sx=2.5 mm
sy= 3.0 mm
5 mm Beam
Geom. Select
A, Baldini, Roma 1 Febbraio 2005
2-electron veto
2
Risoluzione temporale misurata
A, Baldini, Roma 1 Febbraio 2005
3
Validation test in COBRA (dec 04)
Pulsed Laser
101 ps
From
COBRA
center
105 cm
25 cm
19.5º
B
A, Baldini, Roma 1 Febbraio 2005
98 ps
21.5
B
4
Prototipo per la misura del tempo con
discriminazione a due soglie
LLTh
1
DLY
DL
3
&
S_In
DH
4
2
HLTh
Realizzazione di un modulo di elettronica NIM a 8
canali
A, Baldini, Roma 1 Febbraio 2005
5
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.
A, Baldini, Roma 1 Febbraio 2005
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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
LP Front face Lateral face
–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
7
8
•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
A, Baldini, Roma 1 Febbraio 2005
9
Small displacement of the two front wires
LXe
GXe
10
PMT alpha direction
11
Charge vs Cos in LXe
Front Face
Data
MC
12
LXe/MC
New PMTs
4 front
sources
Old PMTs
13
LXe/MC
4 front
sources
After applying QEs
14
Towards the final calorimeter
70 kHz photons with E>5 MeV from muon radiative decay @ R() 3x10**7.
Total sources rate O(15 KBq @ 5 MeV)
15
Po half-life=138 days
Trigger was
changed several
times …
16
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 !
A, Baldini, Roma 1 Febbraio 2005
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WIRE SOURCES FOR FINAL CALORIMETER
15 WIRES, 5 DOT-SOURCES PER WIRE
150 cm total wire length
12.4 cm distance between Am dots
Central Dot
20.0 cm distance between Mark and First Dot
Am dots
Reference Mark
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
A, Baldini, Roma 1 Febbraio 2005
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rather narrow
energy-spectra
possible mounting
on special
supports and screws
A, Baldini, Roma 1 Febbraio 2005
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b) 9 MeV gamma line from neutron capture on
Nickel:Experimental set-up
- Am-Be source
(20000 n/s);
- Polyethylene;
- Nickel plates
30 x 30 cm2
(0.5 cm and 0.25 cm
thickness)
- 20 x 20 x 36 cm3
NaI detector
-MCA ORTEC
(2048 channels)
- NIM electronics.
A, Baldini, Roma 1 Febbraio 2005
20
γ-line from n-capture on Ni, I, Al, H2;
natural radioactivity Tl, K; Am/Be source
K
1.46 MeV
H2
Am/Be
2.2 MeV 4.4 MeV &
1st escape
Tl
I
2.6 MeV
6.8 Mev
Ni
8.54 MeV &
1st escape
Al
7.7 MeV
Ni
9 MeV
Black: Am/Be source and 1 cm Ni
Red: no Am/Be source
Green: no Am-Be source, no Ni
(Gotta Beam on)
A, Baldini, Roma 1 Febbraio 2005
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THERMAL NEUTRON CAPTURE ON NICKEL
D + H  He + n Q = 3.27 MeV
Potentialities :
D + 3H  4He + n Q = 17.59 MeV
• 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)
2
neutron generator (Pavia ?)
3
• 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
A, Baldini, Roma 1 Febbraio 2005
9 MeV Nickel γ-line
NaI 20 x 20 x 36 cm3
Polyethylene
3 cm 20 cm
22
0.25 cm Nickel plate
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 2005
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c) ULTERIORI POSSIBILITA’
500 KV PROTON ACCELERATOAND LITIUM TARGET FOR A
17.6 MEV GAMMA LINE
3
7Li
(p,)48Be
[P.R. 73, 666 (1948), N.P. 21 1 (1960), Zeitschrift f. Physik A351 229 (1995)]
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; p29 MeV/c
• 500 KeV and criticality of an air-insulated accelerator
• is a post-acceleration possible ?
A, Baldini, Roma 1 Febbraio 2005
24
PREVIOUS
  e 
EXPERIMENT
1982 !!
A, Baldini, Roma 1 Febbraio 2005
25
NOW: GLAST SPACE EXPERIMENT
CRYSTAL CALORIMETER CALIBRATION
180 cm target-pipe
It is the old VDG of the Crystal Ball experiment ! !
they have some problems: old device, max. VDG p-energy is 400 KeV
out of resonance: -rate reduced by factor  5000
Stiamo discutendo sui possibili modi per l’approvvigionamento di un
acceleratore adatto ai nostri scopi
A, Baldini, Roma 1 Febbraio 2005
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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 2005
27
4) Cryostat: designs ready; tenders
and procurements organization
Tenders have been organized in three parts:
1. Conventional part
Finanziato nel 2004 (200 K€)
2. Cold and warm windows O.
3. Purchasing of the cold sealing O.
Totale offerte e stima
circa 160 K€
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.
A, Baldini, Roma 1 Febbraio 2005
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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 2005
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FEA studies are in progress
200000000
180000000
160000000
max principal ( Pa )
140000000
120000000
100000000
80000000
60000000
40000000
20000000
0
0,0003
0,0004
0,0006
0,001
thickness ( m )
cerniera max princ-thickness
membrane theory
200000000
0,0005
180000000
0,00045
160000000
0,0004
140000000
max principal ( Pa )
max displacement ( m)
0,00035
0,0003
0,00025
0,0002
0,00015
120000000
100000000
80000000
60000000
0,0001
40000000
0,00005
20000000
0
0,0003
0,0004
0,0006
thickness ( m )
incastro max
cerniera
max displ-thickness
A, Baldini, Roma
1displ-thickness
Febbraio
2005
0,001
0
0,0003
0,0004
0,0006
thickness ( m )
Incastro max princ-thickness
membrane theory
0,001
30
Honeycomb structure discussed with manufacturing company
Honeycomb structure
Two facing of .7 mm CFRP.
(intermediate high module CF with
Epoxy space approved)
Core aluminum honeycomb
perforated
This area is reinforced
Bolted area
A, Baldini,
Roma 1 Febbraio 2005
Internal welded foil .3 mm or less welded on external
Frame necessary to test the window prior the final welding
on the cryostat body.
31
Honeycomb structure has been discussed with manufacturing
company
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
Precision must been obtained on
this side for this reason the
honeycomb must rest on the
mold on this side
A, Baldini, Roma 1 Febbraio 2005
32
Cold joints: interaction with the factory
Modification of bolts position and number
We asked a seal no-magnetic
A, Baldini, Roma 1 Febbraio 2005
33
Cold joints
A, Baldini, Roma 1 Febbraio 2005
Pisa 30-December-2004
34
Struttura di supporto dei PMT: disegno
pronto
A, Baldini, Roma 1 Febbraio 2005
35
4) PMTs
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
A, Baldini, Roma 1 Febbraio 2005
36
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
A, Baldini, Roma 1 Febbraio 2005
(110 ZA = 170 K€)
37
Dal MoU di MEG
Appendix 1. INFN contribution to the different subdetectors
Item
LXe cryostat
400
PMTs test and
purchase
600
Timing counter
700
Splitters
100
Trigger
400
Total
A, Baldini, Roma 1 Febbraio 2005
Cost
(K€)
2200
38
Stime di costo aggiornate
Previsioni
Assegnazioni Risparmi
LXenon
Trigger
• PMT
• Criostato
Timing counter
500 K€ -100K€
200 K€ (criostato)
160 K€ (supporto +
finestre)
-40K€
• APD + fibre (interno)
• PMT (100: esterno)
(160) 130K€
-30 K€
(315) 135 K€
-180 K€
• Scintillatore
50 K€
• Calibrazione
100 K€
• Meccanica
Risparmio totale
60 K€
-225K€
(rispetto ai 700 K€)
• Prototipi
• Sistema completo
100+160 K€
-100 K€
Splitters
• Sistema completo
115 K€
+15 K€
TOTALE MoU
2200 K€
Assegnato
1155 K€
Previsto finale
1750 K€
Risparmio
450 K€
Non previsti:
Software
22.5 K€
Calibrazioni 50 K€
PMT
A, Baldini, Roma 1 Febbraio 2005
40 K€
170 K€
242.5 K€
39
Fine
A, Baldini, Roma 1 Febbraio 2005
40
Zener diodes in the last two ampl.
stages of the base
presently installed
T=-108ºC
PMT with Zener
41
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
42
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.
43
Results: FairChild
68+75
5 Hz
75+75
200 Hz
(75//75)x2
3 Hz
44
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 ?
A, Baldini, Roma 1 Febbraio 2005
45