In-Air X-ray detectors

a new field of extremely simple and powerful

beam diagnostics

BIW06 Fermilab 1-4 May 2006

Kees Scheidt ESRF

a tiny fraction (~2.10-6 = 300uW/mrad) traverses the crotch : Xrays >150KeV

= 155W/mrad40mm Cu & 5mm Fe

1,E+00

1,E+02

1,E+04

1,E+06

1,E+08

1,E+10

1,E+12

1,E+14

0,0001 0,001 0,01 0,1 1 10 100 1000

IR Vis.

X-rays

Ec=20KeV

thisdevice

200 KeV

Side-View i.e. in the vertical plane of the beam

vertical

ho

rizo

nta

l

Vertical profile

measurement time = 1 millisec

Imaging :

scintillator +optics +camera

Electric :

Lead-Blade-BPM

2 types of In-Air X-ray detectors :

In-Air Lead-Blade-monitor for Vertical Beam Motion (v=35m)installed behind crotch of Cell 5

+50V

I [upto uA]

~130um fwhm

~1000um

~1000um

A E

B

CD

V

um

P

P

> 1uA

+50V

What is creating this current ?

In : Xray = 1011 photons/sec

Out :1uA= 1013 electrons/sec

Showers of secondary particles,created themselves by the interaction of X-photons with Lead,cause the air-particles to ionise.

V

S

S

vertically adjusted so thatUpper Blade intercepts~50% of the X-ray beam :

detector with extreme sensitivity to vertical beam motion

+50V

I

t [sec]

multiple10um steps

[V]

limited linearity range (about +/- 20um)

In-Air X-ray detectors

BIW06, FermiLab, May1-4

Conclusions :

Lead-Blade-Monitor :

analysis after cross-comparison with other diagnostics(classical X-BPMs, CO-BPMs, F-BPMs, and ID-25-fast) :

more performance . . . for much less complexity !!

if installed behind a large number (16, 32, 64max.) of crotches they would form an excellent global vertical stability monitor system for both DC and AC.

8 installations foreseen in 2006 (for survey purposes only)

In 2007 possibly more installations andintegration into the global feedback system.

Why are In-Air X-ray detectors so powerful ? :

1) Excellent conversion efficiency of the detector material :

- CdWO4 for the Imaging devices- Lead,Tungsten or Gold for the Blade-Monitor

2) They touch the heart of the beam, other diagnostics can not reach there and get much smaller signal from the edges or tails

3) The 6GeV ESRF has nice crotches !! (40mm is not too thick)

But can they find application in medium energy light sources ??

ESRF dipole

200KeV

Soleil

Diamond

emitted Hard X-rays : Flux comparison 6 GeV ESRF with Soleil & Diamond

ANKA 2.5 GeVKarlsruheGermany

ANKA 2.5 GeVKarlsruheGermany

ANKAPeak Energyat 80KeV

ESRFPeak Energyat 170KeV

1E-7=3.4uW/mrad2E-6=300uW/mrad

ANKA 2.5 GeVKarlsruheGermany

vertical profile ANKA

2.5 GeVKarlsruheGermany

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

326 327 328 329 330 331 332 333Current of Quadrupole Family 2 [A]

Ver

tica

l B

eam

Siz

e [s

mm

]

XraysVisible

ANKA 2.5 GeVKarlsruheGermany

ESRF TransferLine2 6 GeV 5mA 1us

beamsize ~130um fwhm

beamsize ~430um fwhm

ESRF TL-2Xrays-In-Aird~2m, ~10mm FeE~75KeVph.div.~66urad

I=5mA, 1uSVertical profiles for

different quadrupole currents