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
A, Baldini, Pisa 10 maggio 2005
Lecce)
1
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
A, Baldini, Pisa 10 maggio 2005
2
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
A, Baldini, Pisa 10 maggio 2005
3
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
•
Test @ BTF: december
Under study (advance status)
•
TC bag
• TCPisa
curved
detector
A, Baldini,
10 maggio
2005 pattern generator
l
d
DR
h
l
4
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.
APD
Kapton Flex.
Black
Coating
Electronics boards
-10 channels
Scint. Fibers
Transition
board
Copper Cold
Finger(~20°)
Peltier Cell
Heat
Exchanger
A, Baldini, Pisa 10 maggio 2005
5
TC bag inside cobra
prototype
design under study. Plastics considered: EVOH,
SARAN, FEP, Nylon 6, TEP Polyamide
A, Baldini, Pisa 10 maggio 2005
6
TC curved (trigger & pattern):
APD test system
APD
Copper
block
Splitters
Pulsed
Laser
Peltier Cell
Integrating
Calibrated
Photometer
1/1000
attenuator
Fast
Photodiode
Photomultiplier
A, Baldini, Pisa 10 maggio 2005
7
Test of the CMS APDs
(90%
acceptance)
I dark vs H.V. Temperature 20°C
1.00E+01
I Dark @ 10Mohm (Volts)
1.00E+00
1.00E-01
1.00E-02
1.00E-03
2.50E+02
3.00E+02
3.50E+02
4.00E+02
H.V. (Volts)
A, Baldini, Pisa 10 maggio 2005
4.50E+02
5.00E+02
APD0210117506_20ID_M
APD0107115426_20ID_M
APD8411087442_20ID_M
APD8418088162_20ID_M
APD8223084713_20ID_M
APD8201082393_20ID_M
APD1910145247_20ID_M
APD8024081013_20ID_M
APD8007079173_20ID_M
APD791478311_20ID_M
APD1908145087_20ID_M
APD1905144927_20ID_M
APD1906145007_20ID_M
APD1909145167_20ID_M
APD1913145407_20ID_M
APD1902144767_20ID_M
APD1903144847_20ID_M
APD1911145327_20ID_M
APD8206082873_20ID_M
APD1222134415_20ID_M
APD1212133615_20ID_M
APD1211133535_20ID_M
APD1213133695_20ID_M
APD1218134175_20ID_M
APD8710092535_20ID_M
APD8810094569_20ID_M
APD8822095449_20ID_M
APD8709092455_20ID_M
APD8722093575_20ID_M
APD8711092615_20ID_M
APD8811094649_20ID_M
APD8619091391_20ID_M
APD8601089791_20ID_M
APD1512138823_20ID_M
APD1511138743_20ID_M
APD1822144554_20ID_M
APD1812143994_20ID_M
APD1704141813_20ID_M
APD1720142933_20ID_M
APD1613140756_20ID_M
APD1611140596_20ID_M
APD1612140676_20ID_M
APD1616140996_20ID_M
APDJA0296_20ID_M
APDJA0302_20ID_M
APDJA0288_20ID_M
APDJA0307_20ID_M
APDJA0312_20ID_M
APDJA0308_20ID_M
APDJA0309_20ID_M
APDJA0311_20ID_M
APDJA0295_20ID_M
APDJA0289_20ID_M
APDJa0290_20ID_M
APDJA0292_20ID_M
APDJA0294_20ID_M
APDJA0316_20ID_M
APDJA0304_20ID_M
APDJA0305_20ID_M
8
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.
A, Baldini, Pisa 10 maggio 2005
9
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)
A, Baldini, Pisa 10 maggio 2005
10
QE systematics
A, Baldini, Pisa 10 maggio 2005
11
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
gain corrected
A, Baldini, Pisa 10 maggio 2005
12
Metodi di calibrazione e monitor per il calorimetro di MEG
e per tutto l’esperimento
Nota interna MEG
(MEG-TN027)
per la CSN1
A, Baldini, Pisa 10 maggio 2005
13
Il controllo del calorimetro e.m. di MEG a rate di
decadimento elevati e variabili
Beam Intensity~5 107 µ/s
BR µ e ~10-13
richiede
• 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 !
A, Baldini, Pisa 10 maggio 2005
14
1) Am SOURCES ON WIRE AND WALLS
Sources in production.
Soon available for all LXe devices.
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
Wire presently mounted in “Large Prototype”
detectors !!
Open problems:
• will the method be usable under full intensity beam conditions ?
To be verified by test !
A, Baldini, Pisa 10 maggio 2005
15
reconstruction of the 8 -source positions in gaseous Xe.
Recent measurement with the large-prototype.
(Po-source produced in Genoa)
A, Baldini, Pisa 10 maggio 2005
16
RINGS
IN
LIQUID XENON
-range (2µm) and
wire shadow (100 µm)
reflection on Al
the ring radius
has some dependence on
the Rayleigh scattering length
in LXe
A, Baldini, Pisa 10 maggio 2005
17
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.
A, Baldini, Pisa 10 maggio 2005
18
A, Baldini, Pisa 10 maggio 2005
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MEG internal note e poi NIM collaboration paper
A, Baldini, Pisa 10 maggio 2005
20
2)THERMAL NEUTRON CAPTURE ON NICKEL
D + 2H
+ 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)
neutron generator
3He
• Intensities from 106 n/s to 108 n/s
• Typical pulse rate and pulse width 10 Hz and 1 _s
• Time separation of direct from delayed reactions
• Single pulse mode
A, Baldini, Pisa 10 maggio 2005
9 MeV Nickel _-line
NaI 20 x 20 x 36 cm3
Tg-on
e5 beam on
Tg-off
Polyethylene
3 cm 20 cm
21
0.25 cm Nickel plate
large-prototype
NaI
/E=2.5%
in the large-prototype
the line is worse.....
the measurement must be
repeated, protecting LXe from
thermal neutrons by a Boron-foil
9 /(generated neutron)2x10-3
A, Baldini, Pisa 10 maggio 2005
22
3)0
calibration…
Support structure: straightly up and
down
Tilt mechanism at every height for
NaI front to face target direction.
Anti
Counter
• Proton beam: 1.8mA
tilt
• 0 Rate: 106 0/sec
0
How often can it be
performed?
up
Target
• Collimate: 2PMTs x 2PMTs ~ 150cm2
(1 position)
down • 1 /sec
target
• # of PMTs on incident face: 216
PMTs (54 positions)
• required: 10,000 evts/position
• takes 10,000 x 54=540,000 s ~
A, Baldini, Pisa 10 maggio 2005
+ time for movements !!
6 d
23
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 RESULTS
A FULL TEST OF THE WIRE CHAMBERS
CAN ALSO BE PERFORMED !
A, Baldini, Pisa 10 maggio 2005
24
Un evento
Hydrogen target
+ Tungsten converter
Photon
A, Baldini, Pisa 10 maggio 2005
Electron
Positron
25
Rough estimate of the time
needed for the LXe calibration
<> (20 ÷ 30)/105/10 = (20 ÷ 30) x 10-6
R = R0 x <> =
Solid angle factor
(R0/106) x 106 x (20 ÷ 30) x 10-6 = (20 ÷ 30) x (R0/106) Hz
¬ Events/day 8.64 x 104 R 2 x 106 x (R0/106)
¬ Assuming 50 locations to be calibrated
(216 PMTs in groups of 4):
Events/day/location 4 x 104 x (R0/106)
largely sufficient....
A, Baldini, Pisa 10 maggio 2005
26
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
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
A, Baldini, Pisa 10 maggio 2005
27
4) 500 KV PROTON ACCELERATOR AND LITIUM TARGET FOR
A
17.6 MEV GAMMA LINE
7
3 Li
(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
• obtainable : at resonance (E p = 440 keV 14 keV)
106 /s (isotropic) for Ip 50 µA
• 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
A, Baldini, Pisa 10 maggio 2005
28
7
3 Li
(p,)48Be
resonant at Ep= 440 keV
=14 keV peak = 5 mb
E0 = 17.6 MeV
E1 = 14.6
Bpeak
6.1
0/(0+ 1)= 0.72±0.07
NaI 12”x12” spectrum
Crystal Ball Data
0
1
A, Baldini, Pisa 10 maggio 2005
29
another interesting possibility......
11
5 B
Cecil et al. NP A539 75 (1992)
10x10 cm NaI crystal
(p,)612C
resonant at Ep= 163 keV
= 7 keV
E0 = 16.1 MeV peak = 5.5 µb
E1 = 11.7 + 4.4 peak = 152 µb
750
0/s (isotropic)
20.000 1/s for Ip 50 µA
lower proton energy !
lower rate at 50 µA !!
A, Baldini, Pisa 10 maggio 2005
30
the High Voltage Engineering
0.5 MeV Cockroft & Walton
model: “coaxial SINGLETRON”
with H+ plasma source
A, Baldini, Pisa 10 maggio 2005
31
Cal. calibration from the target position, monitoring at the cal. back
rails
cockroft
focusing elements
(magnetic or electrostatic ?)
at the cal. back the proton motion in the COBRA field must be studied
A, Baldini, Pisa 10 maggio 2005
32
proton MC trajectories
Plane Z = 0 cm
Ep 440 keV 28 MeV/c !!
Y(cm)
_ ~0.8cm
_ ~ 0.5° giroradius < 1 cm
(_ ~ 8° giroradius < 12 cm)
X(cm)
A, Baldini, Pisa 10 maggio 2005
Z(cm)
the protons are not reflected back by
the varying magnetic field
33
The old Van der Graaf of the previous µ e experiment .......
generates an e+ e– pair, at 17.6 MeV, seen in the GLAST calorimeter
A, Baldini, Pisa 10 maggio 2005
34
RADIO FREQUENCY QUADRUPOLE ACCELERATOR
• practically monoenergetic
• pulsed operation; frequency 100 Hz 100 µs pulses
• average current 50 µA , 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
A, Baldini, Pisa 10 maggio 2005
35
A, Baldini, Pisa 10 maggio 2005
36
attempt to grade the different C&M methods
A, Baldini, Pisa 10 maggio 2005
37
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
2
E
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)
A, Baldini, Pisa 10 maggio 2005
38
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, Pisa 10 maggio 2005
Cost
(K)
2200
39
Stime di costo aggiornate
Previsioni
LXenon
• 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
(rispetto ai 700 K)
Assegnazioni Risparmi
Trigger
A, Baldini, Pisa 10 maggio 2005
60 K
-225K
• Prototipi
40 K
• Sistema completo
-100 K
Splitters
• Sistema completo
Non previsti:
• Software
22 K
• Calibrazioni 50 K
• PMT
145+115 K
115 K
+15 K
242 K
170 K
TOTALE MoU
2200 K
Assegnato
1602 K
Previsto finale
1992 K
Risparmio
208 K
40
Budget (K)
Calorimeter PMT
Lxe
Vessel
Various items
Xe system
Cobra Magnet
1756
845
400
271
369
1175
Timing counter
Trigger
700
400
Drift Chambers
Muon transport
DAQ Electronics
Detectors environment
HV
149
184
405
172
39
6865
Japan
Italy
PSI
2529
2200
1299
6028
Running costs - 2008
A, Baldini, Pisa 10 maggio 2005
+700 (400 PMT)
+500 (aumento costo Xenon:
non previsto)
1303
41