photons in the universewolle/telekolleg/kern/lecture/...lorentz factor: ๐พ๐พ= 1...
TRANSCRIPT
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Spectral lines of hydrogen
absorption
hydr
ogen
gas
absorption spectrum
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Element production on the sun
5
Hydrogen emission spectrum
wave length nm
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Spectral analysis
6
H
Spectral analysis Kirchhoff und Bunsen: Every element has a characteristic emission band
Max Planck
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Nuclear Resonance Fluorescence
Nuclear Resonance Fluorescence (NRF) is analogous to atomic resonance fluorescence but depends upon the number of protons AND the number of neutrons in the nucleus
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Photon-nuclear reactions with MeV ฮณ-rays
pure electromagnetic interaction spin selectivity (mainly E1, M1, E2 transitions)
ฮณ-ray
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Photon-nuclear reactions with MeV ฮณ-rays ฮณ-ray pure electromagnetic interaction
spin selectivity (mainly E1, M1, E2 transitions)
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Low energy photon scattering at S-DALINAC
โwhiteโ photon spectrum wide energy region examined
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Principle of measurement and self absorption
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
First ฮณฮณ-coincidences in a ฮณ-beam
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
First ฮณฮณ-coincidences in a ฮณ-beam
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
First ฮณฮณ-coincidences in a ฮณ-beam
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Total power received by Earth from the Sun
174 Peta (1015) Watt
@ extreme light infrastructure, Europe
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Compton scattering and inverse Compton scattering
Compton scattering:
Elastic scattering of a high-energy ฮณ-ray on a free electron. A fraction of the ฮณ-ray energy is transferred to the electron. The wave length of the scattered ฮณ-ray is increased: ฮปโ > ฮป.
โ๐๐ โฅ ๐๐๐๐๐๐2
๐ธ๐ธ๐พ๐พโฒ =๐ธ๐ธ๐พ๐พ
1 +๐ธ๐ธ๐พ๐พ๐๐๐๐๐๐2
โ 1 โ ๐๐๐๐๐๐๐๐
Inverse Compton scattering:
Scattering of low energy photons on ultra-relativistic electrons. Kinetic energy is transferred from the electron to the photon. The wave length of the scattered ฮณ-ray is decreased: ฮปโ < ฮป.
๐๐โฒ โ ๐๐ โ1 โ ๐ฝ๐ฝ โ ๐๐๐๐๐๐๐๐๐พ๐พ1 + ๐ฝ๐ฝ โ ๐๐๐๐๐๐๐๐๐ฟ๐ฟ
๐๐โฒ โ ๐๐ =โ๐๐๐๐๐๐
โ 1 โ ๐๐๐๐๐๐๐๐๐พ๐พ
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Inverse Compton scattering
Electron is moving at relativistic velocity Transformation from laboratory frame to reference frame of e- (rest frame):
in order to repeat the derivation for Compton scattering
๐ธ๐ธ๐พ๐พ = ๐พ๐พ โ ๐ธ๐ธ๐พ๐พ 1 โ๐ฃ๐ฃ๐๐๐๐๐๐๐๐๐๐๐๐โ๐พ๐พ
Doppler shift
Lorentz factor: ๐พ๐พ = 1 โ ๐ฝ๐ฝ2 โ1/2 = 1 + ๐๐๐๐๐๐๐๐๐๐
931.5โ0.00055
๐ธ๐ธ๐พ๐พโฒ =๐ธ๐ธ๐พ๐พ
1 +๐ธ๐ธ๐พ๐พ๐๐๐๐๐๐2
โ 1 โ ๐๐๐๐๐๐๐๐ Compton scattering in rest frame
๐ธ๐ธ๐พ๐พโฒ = ๐พ๐พ โ ๐ธ๐ธ๐พ๐พโฒ 1 +๐ฃ๐ฃ๐๐๐๐๐๐๐๐๐๐๐๐โ๐พ๐พโฒ
Limit ๐ธ๐ธ๐พ๐พ โช ๐๐๐๐๐๐2
๐ธ๐ธ๐พ๐พโฒ โ ๐พ๐พ2 โ ๐ธ๐ธ๐พ๐พ 1 โ๐ฃ๐ฃ๐๐๐๐๐๐๐๐๐๐๐๐โ๐พ๐พ 1 +
๐ฃ๐ฃ๐๐๐๐๐๐๐๐๐๐๐๐โ๐พ๐พโฒ
transformation into the laboratory frame
๐ธ๐ธ๐พ๐พโฒ โ 4๐พ๐พ2 โ ๐ธ๐ธ๐พ๐พ
electron and ฮณ interaction ๐๐๐๐โ๐พ๐พ~1800 ฮณโ emission relative to electron ๐๐๐๐โ๐พ๐พโฒ~00
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Laser Compton backscattering
Energy โ momentum conservation yields ~4๐พ๐พ2 Doppler upshift Thomsons scattering cross section is very small (6ยท10-25 cm2)
High photon and electron density are required
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Gamma rays resulting after inverse Compton scattering
A. H. Compton Nobel Prize 1927
photon scattering on relativistic electrons (ฮณ >> 1)
โ๐๐ = 2.3 eV โก 515 ๐๐๐๐
๐๐๐๐๐๐๐๐๐๐ = 720 ๐๐๐๐๐๐ โ ๐พ๐พ๐๐ = 1 +๐๐๐๐๐๐๐๐๐๐ ๐๐๐๐๐๐
931.5 โ ๐ด๐ด๐๐ ๐ข๐ข= 1410
๐ธ๐ธ๐พ๐พ = 2๐พ๐พ๐๐21 + ๐๐๐๐๐๐๐๐๐ฟ๐ฟ
1 + ๐พ๐พ๐๐๐๐๐พ๐พ2 + ๐๐02 + 4๐พ๐พ๐๐๐ธ๐ธ๐ฟ๐ฟ
๐๐๐๐2โ ๐ธ๐ธ๐ฟ๐ฟ
4๐พ๐พ๐๐๐ธ๐ธ๐ฟ๐ฟ๐๐๐๐2
= recoil parameter
๐๐๐ฟ๐ฟ = ๐๐๐ธ๐ธ๐๐๐๐๐ฟ๐ฟ๐๐
= normalized potential vector of the laser field
E = laser electric field strength ๐ธ๐ธ๐ฟ๐ฟ = โ๐๐๐ฟ๐ฟ
๐พ๐พ๐๐ = ๐ธ๐ธ๐๐๐๐๐๐2
= 11โ๐ฝ๐ฝ2
= Lorentz factor
maximum frequency amplification: head-on collision (ฮธL = 00) & backscattering (ฮธฮณ = 00)
๐ธ๐ธ๐พ๐พ~4๐พ๐พ๐๐2 โ ๐ธ๐ธ๐ฟ๐ฟ โ 18.3 ๐๐๐๐๐๐
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Scattered photons in collision
Luminosity: ๐ฟ๐ฟ = ๐๐๐ฟ๐ฟโ๐๐๐๐4๐๐โ๐๐๐ ๐
2
๐๐๐ฟ๐ฟ = 0.5 ๐ฝ๐ฝ โ๐๐๐ฟ๐ฟ = 2.4 ๐๐๐๐ = 3.86 โ 10โ19 ๐ฝ๐ฝ โก 515 ๐๐๐๐
โ ๐๐๐ฟ๐ฟ= 1.3 โ 1018
๐๐๐ ๐ = 15 ๐๐๐๐
๐๐ = 1 ๐๐๐๐
โ ๐๐๐๐= 6.25 โ 109
โ ๐๐
ฮณ-ray rate: ๐๐๐พ๐พ = ๐ฟ๐ฟ โ ๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐ ๐๐๐๐ = 0.67 โ 10โ24 ๐๐๐๐2
โ 2.9 โ 1032 โ ๐๐ ๐๐๐๐โ2๐๐โ1
โ 2 โ 108 โ ๐๐ ๐๐โ1 (full spectrum)
Yb: Yag J-class laser
10 Peta (1015) Watt
repetition rate: ๐๐ = 3.2 ๐๐๐๐๐๐
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Thomson Scattering
J. J. Thomson Nobel prize 1906
Thomson scattering = elastic scattering of electromagnetic radiation by an electron at rest โ the electric and magnetic components of the incident wave act on the electron โ the electron acceleration is mainly due to the electric field โ the electron will move in the direction of the oscillating electric field โ the moving electron will radiate electromagnetic dipole radiation โ the radiation is emitted mostly in a direction perpendicular to the motion of the electron โ the radiation will be polarized in a direction along the electron motion
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Thomson Scattering
J. J. Thomson Nobel prize 1906
๐๐๐๐๐๐ ๐๐๐๐ฮฉ
=12๐๐02 โ 1 + ๐๐๐๐๐๐2๐๐
๐๐0 =๐๐2
4๐๐๐๐0๐๐๐๐๐๐2= 2.818 โ 10โ15 ๐๐
๐๐๐๐ = ๏ฟฝ๐๐๐๐๐๐ ๐๐๐๐ฮฉ
๐๐ฮฉ =2๐๐๐๐02
2๏ฟฝ 1 + ๐๐๐๐๐๐2๐๐ ๐๐๐๐๐๐
0
=8๐๐3๐๐02 = 6.65 โ 10โ29 ๐๐2 = 0.665 ๐๐
differential cross section
classical electron radius
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Scattered photons in collision
ฮธ = 0 ฮธ = ฯ
๐ธ๐ธ๐พ๐พ = 2๐พ๐พ๐๐21 + ๐๐๐๐๐๐๐๐๐ฟ๐ฟ
1 + ๐พ๐พ๐๐๐๐๐พ๐พ2 + ๐๐02 + 4๐พ๐พ๐๐๐ธ๐ธ๐ฟ๐ฟ
๐๐๐๐2โ ๐ธ๐ธ๐ฟ๐ฟ
๐๐๐ ๐ ๐๐๐๐ = 1/๐พ๐พ
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Inverse Compton scattering of laser light
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Extreme Light Infrastructure โ Nuclear Physics
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Nuclear Resonance Fluorescence
Widths of particle-bound states: ฮ โค 10๐๐๐๐
Breit-Wigner absorption resonance curve for isolated resonance:
๐๐๐๐ ๐ธ๐ธ = ๐๐๏ฟฝฬ ๏ฟฝ๐22๐ฝ๐ฝ + 1
2ฮ0ฮ
๐ธ๐ธ โ ๐ธ๐ธ๐๐ 2 + ฮ 2โ 2 ~ ฮ0 ฮโ
Resonance cross section can be very large: ๐๐0 โ 200 ๐๐ (for ฮ0 = ฮ, 5 MeV)
Example: 10 mg, A~200 โ Ntarget = 3ยท1019, Nฮณ = 100, event rate = 0.6 [s-1]
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Nuclear Resonance Fluorescence
Count rate estimate 104 ฮณ/(s eV) in 100 macro pulses 100 ฮณ/(s eV) per macro pulse example: 10 mg, A ~ 200 target resonance width ฮ = 1 eV 2 excitations per macro pulse 0.6 photons per macro pulse in detector pp-count rate 6 Hz 1000 counts per 3 min
8 HPGe detectors 2 rings at 900 and 1270
ฮตrel(HPGe) = 100% solid angle ~ 1% photopeak ฮตpp ~ 3%
narrow band width 0.5%
Hans-Jรผrgen Wollersheim - 2017 Indian Institute of Technology Ropar
Nuclear Resonance Fluorescence
narrow bandwidth allows selective excitation and detection of decay channels