Transcript A new tile calorimeter with Silicon Photomultipliers for the KLOE-2 experiment

A new tile calorimeter with
Silicon Photomultipliers for
the KLOE-2 experiment
Ivano Sarra
University of Tor Vergata
Laboratori Nazionali di Frascati
Young Researcher Program
@ Frascati Spring School 2008
LNF- Frascati ( 13-5-2008)
Summary ofOutline
the existing QCAL
- The proposal of a new quadrupole calorimeter QCALT
- A new kind of device: the SIPM
- Test on SiPM (Hamamatsu MPPC)
- Test on different fiber types
- Tests on Tiles
- Conclusions
Summaryof
of the
the existing
Summary
existingQCAL
QCAL
At KLOE the measurement of direct CP
violation is possible through the double ratio:
R = G(KL p+p) G(KS p0p0)
/ G(KS p+p) G(KLp0p0)
For the neutral decay of
0
KL ―› 2π ―› 4γ
To recover photons lost
on the quadrupole region
the area is covered by a
Tile Calorimeter QCAL
Proposal of
of new
Proposal
new QCAL
QCAL
For the high precision measurement of KL2p0 decay rate
- Adapt a new calorimeter over new interaction region
- Improve granularity, time resolution & efficiency.
- Barrel with 12 modules
- Each module has a thickness
of 5-6 cm and 1 m length.
It is made by 8 layers of
2 mm W /3 mm Scint.
R
Along Z, each slab is divided in 20 tiles of 5x5 cm2
Tile dimension increases along R.
Z
Z
New tiles
design
New
tile design
The R&D for Tesla/ILC made possible a very promising tile detector:
- Square tiles with fibers in circular grooves.
- Tile readout is possible with SiPM
SIPM =SILICON PHOTOMULTIPLIER
Array of Single Geiger Mode APD. It is a discrete detector for photon
counting depending on the PIXEL size
MPPC = SIPM by Hamamatsu
1 mm^2 area
100 pixels --> 100 um
400 pixels --> 50 um
Test on SiPM
First study
study on
First
on SiPM
SiPM
To study SiPM characteristics we use:
- Black box
- Pulsed led to fire SiPM
- Polaroid filter to change light intensity
We can measure:
- Gain vs Vbias
- Gain vs Temperature
- Dark noise rate
SIPM signal with BLUE Led Pulser
From Scope:
Vbias 69.25Volt, T:24°C
Rise Time ~3ns,
Fall Time ~150ns
From Adc:
0pe
1pe
2pe
3pe
4pe
From ADC spectra, we get
single photoelectron charge
(Vbias 69.25, T:24°C):
Q = 0.36pC
Gain = 2.3E+06
Δcount=17.4
Q’=17.4*0.25pC=4.35pC
Q=4.35/11.8(ampl.)=0.36pC
G=Q/e
Gain vs T
Vbias=69.30V
Our result
ΔG = -0.12 ΔT
Hamamatsu
ΔG=-0.12 ΔT
Dark-Count(kHz)
Dark Count vs Vbias
Our result
Hamamatsu
Test on fibers
Test of single Scintillating Fibers
We have studied the characteristics of 3 different types of fibers:
- Kuraray SCSF 81 (Blue )
- Saint Gobain BCF92 single cladding (Green)
- Saint Gobain BCF92 multi cladding (Green)
The test is performed using SiPM and a beta source of Sr90.
The trigger is provided by a NE110 finger (1cm x 5cm) readout by 1” PM.
Sr90
SiPM + electronics
fiber
Trigger
NE110
PM
Selected Scintillating Fibers
After the test we
have selected:
Saint-Gobain Multi
Cladding fibers:
1) Best light yield
2) Fast emission time
(3-4 ns/p.e.)
3) High attenuation
length (3.5 m)
Q( ADC COUNTS)
Test on tiles
Test of tiles
3 possible solutions under study:
1) SIPM directly on tile
2) SIPM + amplifier + HV on tile
3) SIPM connected to fibers in a
far-away position from tile
At the moment we have tested
only the third solution:
- Tiles: 3mm and 5 mm thickness
- Without reflector at fiber end
- Simple mylar around tile
- SiPM placed outside tile in
optical contact (w grease)
with fiber.
Test of Tiles
 Data taking with cosmic rays.
 Trigger using 2 scintillator counters read at both ends.
Tested 2 tiles with different thickness and different SIPM.
To investigate the use of SIPM@400 pixels (vs SIPM@100 pixels) which has:
 a gain reduction of 1/3 (7.5 10+5 instead 2.4E10+6)
 a reduced temperature dependence DG = -0.03DT (instead -0.12)
NE110
Fiber
Tile
Scintillator
SiPM + electronics
Trigger
Test of Tiles (MIP distribution)
ADC distributions
for two different
thicknesses
The MIP values are
compatible taking into
account different
thicknesses and QE
of the two SIPMs.
N3mm = N5mm
x 3/5
x 0.40/0.45
N3mm ~ 14
3mm thick
400 Pixels SIPM
<MIP> = 14 pe
5mm thick
100 Pixels SIPM
<MIP> = 26 pe
Tile test (time resolution for MIP)
110 ps/counts
5 mm thick
3 mm thick
TDC ( Counts)
 After correcting the pulse height dependence on the timing,
a Time Resolution of 750 (1000) ps is obtained for a MIP
on the 5 (3) mm thick tiles.
 No correction applied to the trigger jitter.
Conclusions and plans
SiPM: our tests confirm Hamamatsu characteristics for 100 pixels MPPC:
- Gain vs HV
- Gain vs temperature
- Dark noise
Reduced temperature variation of gain and dark noise expected for a
400 pixels MPPC (50 m pixel).
Fibers: adopted solution is the Saint Gobain multi cladding.
Tile: Good results on light response and timing.
Light yield and time resolution sufficient for our purposes.
Solution with MPPC+amp directly on tile under development.
Spares
Set Up
- HV stability 10 mV
- Blue LED diode on
SiPM
-Temperature measured
on SiPM
- CAMAC DAQ
- ADC sensitivity
0.25 pC/cnt
Mppc: Multi Pixel
• Foton Counter
Mppc: Multi Pixel Foton Counter -100C N.370, characteristics at 25°C and λ=655 nm:
Vop. 69,28V, Gain 2.41E+6
The KLOE experiment
The KLOE design was driven by the measurement of direct CP violation
through the double ratio: R = G(KL p+p) G(KS p0p0) / G(KS p+p) G(KLp0p0)
Collision at sqrt(s)=Mphi = 1.02GeV
- +
• (e-e+)―› Φ ―› (kS kL) (k k )
Drift Chamber
Measure charged particles
(4 m thick  3.4 m lenght)
 90% He; 10% iC4H10
52140 wires
Electromagnetic
Calorimeter
Measure charged
particles
lead/scint. fibers
4880 PM
Superconducting coil
B=6kGauss
Dark Count shape vs Vbias
T = 24 °C
•
V=R*I=R*Q/τ,
Vbias 68.90V
Vbias 68.97V
0.5pe
470kHz
0.5pe
530kHz
1.5pe
34kHz
1.5pe
40kHz
Where:
τ = 35ns
R = 50Ω
•Dark rate follows
•specifications.
•It becomes negligible
•when triggering at
•1.5 pe.
Vbias 69.03V
Vbias 69.09V
0.5pe
610kHz
0.5pe
680kHz
1.5pe
58kHz
1.5pe
85kHz
Tile test
Time resolution
measured using
different number of
photoelectrons on tile.
t 
4.8 ns
 0.37 ns
N pe
Result compatible with 5mm
tile.
No trigger jitter corrected.
Stochastic term roughly
consistent with:
 fib   sc int   3.5  2.5  ns
 fib   sc int  4.3 ns
Fibers test
Saint Gobain
multi cladding
0pe
1pe
- Pedestal
- Cut @ 0.5 pe
- Cut @ 1.5 pe
2pe
3pe
4pe
5pe
Fibers test
Saint Gobain
single cladding
1pe
0pe
- Pedestal
- Cut @ 0.5 pe
2pe
- Cut @ 1.5 pe
3pe
4pe
Fibers test
Kuraray Y11
0pe
1pe
- Pedestal
- Cut @ 0.5 pe
- Cut @ 1.5 pe
2pe
3pe
Entries
Tile test
ADC distribution
obtained using a 3mm
tile optically coupled
with a 400 pixels
SiPM.
0pe
1pe
ADC counts
Tile test
Using 3mm tile with
400 pixels MPPC.
TDC
Slewing correction.
ADC
Vs
Fit function:
B
t0  A 
a0  a ped
Charge of imput signal [ADC counts]
Apd operanti in Geiger Mode
Diodo a Vbias > Vbd
i
• t < t0 ... i=0, non ci sono portatori
imax
• t = t0, inizia la valanga
• t0 < t < t1, la valanga si diffonde
• t > t1, la valanga si auto-sostiene ed è
limitata ad Imax dalle resistenze in serie
t0 t1
Meccanismo di Quencing
Vbias
Vbd
t
Apd operanti in Geiger Mode
Gli Apd operanti in geiger mode possono essere modellati tramite il
seguente circuito elettronico:
• Switch Open: quando la valanga non è
innescata Cd si carica a Vbias e non
scorre corrente
• Switch Close: quando la valanga si
innesca Cd si scarica fino a Vbd con
τ=Rs*Cd e la corrente va ad
I=(Vbias-Vbd)/RQ
τQ=RQ*Cd=35ns
Gain vs Vbias.2
From Hamamatsu:
Our measurement:
Gain vs Vbias
ADC spectra as a function of the
applied HV.
Vbias 68.60V
Vbias 68.66V
Vbias 68.75V
Vbias 68.81V
Gate: 350ns
T=24°C
Vbias 68.70V
Vbias 68.87V
Gain vs Vbias
Increasing HV we increase dark rate
Vbias 68.94V
Vbias 69.33V
Vbias 68.99V
Vbias 69.39V
Vbias 69.05V
Vbias 69.45V
Gain vs Vbias
ΔG=2.24 ΔV
ΔG=2.19ΔV
Our result
ΔG=2.12ΔV
Hamamatsu
ΔG=2.25 ΔV