1. B. Azadegan, S. A. Mahdipour Hakim Sabzevari University
Investigation of channeling radiation from diamond crystals to provide a mono energetic x ray at the ELBE electron linear accelerator
B. Azadegan, S. A. Mahdipour
Hakim Sabzevari University

2. Guideline Theory of channeling radiation (CR) Experimental setup
CR measurements on diamond
Intense chaneling radiation source

3. 1. Theory of channeling radiation
Planar channeling: One dimensional problem
Axial channeling: two dimensional problem

4. 1. Theory of channeling radiation
- Lorentz factor
- observation angle
CR properties
quasi-monochromatic
directed
intense
tunable

5. 1. Theory of channeling radiation
Planar channeling
The planar continuum potential of diamond for electrons
Axial channeling
The <100> axial continuum potential of germanium for electrons

6. 1. Theory of channeling radiation
Quantum mechanical model
Channeling
radiation
Wave functions and eigenvalues
CR intensity
CR photon energy

7. 1. Theory of channeling radiation
1→0
Yield (photons/e sr keV)
2→1
Photon energy (keV)
Simulation of the CR spectrum for 42.5 μm thick diamond crystal
Measurment of the CR spectrum for 42.5 μm thick diamond crystal
Yield (photons/e sr keV)
Photon energy (keV)

8. 1. Theory of channeling radiation
(b)
Θ0=0.25 mrad
(a)
Θ0=0.0
Classical model
Planar :
Axial :
Angular energy distribution:

9. 2. Experimental setup
ELBE = Superconducting Electron Linac of
high Brilliance and low Emittance

10. 2. Experimental setup
The Superconducting Electron Linear Accelerator
Parameter
X-rays
Bremsstrahlung
IR, Neutrons, Positrons
Electron beam energy / MeV
8 - 20
Max. bunch charge /pC
0.77 77
Max. average beam current /µA
200
1000
Normalized transverse emittance /mm mrad(rms) 3 20
Normalized longitudinal emittance /keV ps(rms) 50
140
Micropulse duration /ps 2
1 - 10
Micropulse repetition rate /MHz
260 13
Macropulse duration /ms
/ cw
Macropulse repetition rate /Hz
1 - 25

11. Beam parameters for CR:
2. Experimental setup
Radiation physics cave
Quadrupole 1
Quadrupole doublet
Dipole 1
Quadrupole 2
Goniometer chamber
Beam dump
Concrete wall
Beam dump shielding
Dipole 2
Vacuum pipe
Shielding and collimator
Detector with preamplifier
e- beam
Crystal
To the amplifier and MCA
Shutter
Secondary electron monitor
Faraday cup
Parameters of CR from 1 – 0 transition in the (110) plane of diamond
Photon energy ECR ≈ 10 ÷ 70 keV
Flux density YCR ≈ 109 ÷ 1010 s-1cm-2 per 10% 1 m, 100 mA
Beam parameters for CR:
Energy Ee= 10 ÷ 35 MeV ∆Ee≈ 200 keV
Current Ie  0.2 mA
Emittance n rms ~ 3 p mm mrad

12. 3. CR measurements on diamond
Diamond structure: Diamond, Si,Ge
Map of diamond crystal constructed from planar scans
Planar CR out of (110), (111) and (100) planes
Electron energies 14.6, 17, 25, 30 and 34 MeV
Crystal thicknesses 42.5, 102, 168 and 500 μm

13. Processing of the spectra:
3. CR measurements on diamond
Processing of the spectra:
Correction for detector efficiency, selfabsorption and attenuation in window materials
Subtraction of bremsstrahlung background
Approximation of peak profiles for determination of CR parameters
corrected
measured
Ee=17 MeV
CdTe detector
Counting rate
Counting rate
Photon energy (keV)
Photon energy (keV)
Spectra of (110) planar channeling radiation (blue) and bremsstrahlung (green)

14. 3. CR measurements on diamond
Crystal thickness (µm)
Photon energy (keV)
Line width (keV)
Photon yield (ph/(sr e-))
Observed
Calculated
14.6 MeV
42.5
16.58
17.06
1.51
0.87
0.048
0.112
168
16.99
1.80
1.25
0.090
0.223
500
16.47
2.20
1.48
0.149
0.384
17 MeV
21.72
22.23
2.00
0.95
0.059
0.148
22.37
2.47
1.39
0.13
0.295
21.38
2.77
1.90
0.30
0.509
30 MeV
56.19
56.87
5.88
2.29
0.229
0.448
56.22
57.00
6.12
3.32
0.52
0.890
55.06
56.61
11.98
5.77
1.012
1.535
Scaling laws of main CR parameters extracted for the 1→0 transition in the (110) plane of diamond
Conclusions:
Photon energy scales with γ 1.7
Photon yield scales with γ 2.12
Photon yield scales with

15. 4. Intense channeling radiation source
An intense channeling radiation X-ray source came into operation at ELBE
Diamond (110)
Ee=14.6 MeV
dN/dEx (Photon keV-1)
Diamond crystal
Photon energy (keV)
Cooled CR target
CR measured at 0◦ at Ie = 11 nA
CR measured at 90◦at Ie = 80 μA
Bremsstrahlung
CR on-line monitoring at photon rates of 1010 s-1
by means of a Compton spectrometer
CR X-ray source

16. 4. Intense channeling radiation source

17. 1. B. Azadegan, W. Wagner, J. Pawelke, PHYSICAL REVIEW B, 74, 045209, 2006
2. W. Wagner, B. Azadegan, L. SH. Grigoryan, J. Pawelke, EURO PHYSICS LETTER, 78,56004, 2007
3. W. Neubert, B. Azadegan, W. Enghardt, H. Heidel, J. Pawelke, W. Wagner, Nuclear Instruments and Methods in Physics Research B, 245,319, 2007
4. W. Wagner, B. Azadegan, M. Sobiella, J. Steiner, K. Zeil, J. Pawelke, Nuclear Instruments and Methods in Physics Research B, 266,327, 2008
5. B. Azadegan, L. SH. Grigoryan, J. Pawelke,W. Wagner, J. Phys. B, 41, , 2008
6. B. Azadegan, S. Dabagov, The European Physical Journal Plus (EPJ), 126, 58, 2011
7. B. Azadegan, S. Dabagov, W. Wagner, Nuclear Instruments and Methods in Physics Research B, 269, 2098, 2011
9. B. Azadegan, Computer Physics Communication, 184, 1064, 2013
10. B. Azadegan, A. Mahdipour, S. B. Dabagov, W. Wagner, Nuclear Instruments and Methods in Physics Research B, 309,56, 2013
11. B. Azadegan, A. Mahdipour, Nuclear Instruments and Methods in Physics Research B, 316,105, 2013
12. . B. Azadegan, W. Wagner, Nuclear Instruments and Methods in Physics Research B, 342,144, 2015
Thank you