j. pozimski-fets meeting @ ic 10 may 2006 first experiences with the fets pepperpot detector
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J. Pozimski-FETS Meeting @ IC 10 May 2006
First experiences with the FETS pepperpot detector
J. Pozimski-FETS Meeting @ IC 10 May 2006
Experience from IAP setup (C. Gabor)
140604-015.spe43m m
43m
m
Proton current <70µA6 keV beam energy=> ~32 mW/mm2
Main Parameters
-> Phosphor material
-> Grain size (and number of the layer) of the phosphor screen
-> Thickness of the layer
-> Coating (Al reflection layer)
-> Mechanic stability (water glass)
-> electric contact necassary ?Simulations (with TRIM/ SRIM)
are reasonable !
J. Pozimski-FETS Meeting @ IC 10 May 2006
Scintillator material – phosphor powderDecay Time
Efficiency Type Composition Density
[g/cm3]
Max. Emission
[nm] 90% - 10% ph/ e
[15keV e-]
[15keV e-]
P 47 Y2SiO5:Ce ---- 400 55 ns 630 0,184
P 46 Y3Al5O12:Ce 4,55 530 300 ns 256 0,056
P 43 Gd2O2S:Tb 7,3 545 1 ms 550 0,116
P 20 ZnCdS:Ag,Cu 4,2 550 4 ms 715 0,148
P 11 ZnS:Ag 4,09 450 3 ms 600 0,156
Ener
gy
Conve
rsio
n [
(W/n
m)/W
]
Wavelength [nm]
~ Efficiency
~ Emission spectrum
~ Luminescense decay time
-> Max. thickness d ~ 100µm
-> Grain size > 1µm (2 µm)
-> 3-4 layer of phosphor grains
QE > 70% of CCD: 500-750nm
J. Pozimski-FETS Meeting @ IC 10 May 2006
Stopping power and range - basics
ned x
d E
,
0EEnergie
“LSS” ~ v
“Bethe-Bloch”
E
1
x
ES
0x
limdx
dE
nm
eV
Stopping Cross Section
(E)S1
(E)elek
S(E)nukl
S1
, totalNNne
At.1510
2cmeV
J. Pozimski-FETS Meeting @ IC 10 May 2006
Stopping power and range of hydrogen in Phosphor
dE0 )()(
11R
E
EelekSE
nuklSN
0,0E +00
2,0E +01
4,0E +01
6,0E +01
8,0E +01
1,0E +02
1,2E +02
1,4E +02
1,6E +02
1,8E +02
0 400 800 1200 1600 2000
Energy [keV]
Sto
pp
ing
Po
wer
[keV
/µ]
(d E / d x )e le c . [k e V /µ ]
(d E / d x )n u c l. [k e V /µ ]
0
200
400
600
800
1000
1200
0 50 100 150 200
Energy [keV]P
roje
cte
dR
ang
e[n
m]
P ro je c ted R a n ge [nm ]
L on g itu d in a l S trag g lin g
SRIM (SRIM.ORG) simulation: Hydrogen in Scintillator material=> Thickness and grain size
J. Pozimski-FETS Meeting @ IC 10 May 2006
Stopping power and range of hydrogen in Aluminium
Al can improove the photon luminosity by reflecting them into the CCD camera
0
20
40
60
80
100
120
0 20 40 60 80 100 120 140 160 180 200
Energy [keV]
Sto
pp
ing
Po
wer
[ke
V/µ
]
(d E / d x)e lec
(d E / d x)n uc l.
0
100
200
300
400
500
600
700
800
900
1000
0 20 40 60 80 100 120
Energy [keV]
Pro
ject
edR
ang
e[n
m]
P ro jec ted R ang e H -> A l
Lo ng . S tra gg ling H -> A l
J. Pozimski-FETS Meeting @ IC 10 May 2006
Stopping power and range of hydrogen in Phosphor-LEBT
H -> P46; decay tim e: 300nsY 3Al5O 12:C e
D ensity: 2,201 g/cm 3
0
0,2
0,4
0,6
0,8
1
1,2
0 20 40 60 80 100
Energy [keV]
Pro
jec
ted
ran
ge
[µm
]
Projected Range P46
Longitudinal S traggling P46
Stopping power H ->P46(Y 3Al5O 12:C e)
D ichte: 2,201 g/cm 3
0
20
40
60
80
100
0 20 40 60 80 100
Energy [keV]
dE
/dx
[ke
V/µ
m]
E lectronic stopping power
N uclear S topping power
J. Pozimski-FETS Meeting @ IC 10 May 2006
Stopping power and range of hydrogen in Aluminium
Protons in Al
0
20
40
60
80
100
120
0 10 20 30 40
Energy [keV]
Sto
pp
ing
po
wer
[kev
/µm
]
electronic stopping power
nuclear stopping power
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60 70 80
Energy [keV]
Pro
ject
edR
ang
e[n
m]
H->A l; P rojected R ange
H->A l; longitudinal straggling
IAP
-> thickness ~ 25nm ~1/3 range
RAL
-> thickness ~ 50nm ~1/7 range
J. Pozimski-FETS Meeting @ IC 10 May 2006
Pepperpot head after the measurements
Discolouring extends over whole plate onto the aluminium frame
beam lager than expected.
No damage of plate and copper, slight colour patterns on copper
=> from aluminium ?
J. Pozimski-FETS Meeting @ IC 10 May 2006
Scintillator damage patternStrong damage of scintillator surface in the interaction regions, but there was still a signal & pattern shows angular distribution.
It seems that the damage is not a simple hole burnt into the surface.
J. Pozimski-FETS Meeting @ IC 10 May 2006
Comparison between the two experiments
IAP RAL
Beam diameter (mm) 4 70
Beam current (mA) 0.07 10
Beam energy (keV) 6 35
Surface power flux (mW/mm2) 32 285
Surface current flux (mA/mm2) 5.5 8.2
Penetration depth (nm) 200 600
max. Energy loss (keV/m) 35 75
max. power density (W/mm3) 200 620
av. power density (W/mm3) 150 480
J. Pozimski-FETS Meeting @ IC 10 May 2006
Next steps :
Try IAP scintillator - different Al thickness- different grain size- different production method
Try different scintillator- Plastic scintillator (radiation hardness)- Solid crystals (ruby, YAG , - available sizes)
Reduce beam energy - Deceleration
….. ?