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

….. ?