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2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Physics at ELI-NP:
Towards TDRs for Nuclear Resonance
Fluorescence and electron scattering
Norbert Pietralla + group, TU Darmstadt
DAAD BMBF
DAAD
293 MEuro approved: Congratulations!
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
< 18 MeV -ray beam from LCB
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Outline
Nuclear physics with low-energy photons (observables)
Recent experiments at Duke‘s HIS
NRF count-rate estimate for ELI-NP
Sketch NRF TDR (based on HPGe + ancillaries)
Nuclear physics with electrons (e,e‘)
Recent experiments at Darmstadt‘s S-DALINAC
(e,e‘) count-rate estimate for ELI-NP
Sketch (e,e‘) TDR (based on S-DALINAC‘s Q-CLAM spectrometer)
Summary
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Photonuclear Reactions
What happens?
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Photonuclear Reactions
gs
´
Separation
threshold
AX
A´Y
Nuclear Resonance Fluorescence (NRF)
Photoactivation
Photodesintegration
Absorption
(-activation)
´
~ 8 MeV
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Nuclear Resonance Fluorescence
Separation
threshold
Observables
• Excitation Energy Er
• Spin J
• Parity p
• Decay Energies E
• Partial Widths Γi/Γ0
• Multipole Mixing d
• Decay Strengths B(pl)
• Level Width Γ (eV - eV)
• Lifetime t (ps – as)
NRF Theory Background and Facts
Widths of particle-bound states: 10 eV
Single-spin level density: J 104 MeV-1
→ isolated resonances
QM:
Decay law:
Typical lifetime limit: t 100 as
Total width:
Transition rates:
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
NRF cross section
Breit-Wigner absorption resonance curve for isolated resonance
[from Fourier transform: (t) (E) ]
0/
On resonance cross sect.s can be very large: 0 200 b (for 0=, 5 MeV)
However, resonances are very narrow
Thermal motion of target nuclei leads to Gaussian Doppler-broadening of
resonance (typical Doppler width few eV 100s of meV)
Energy-integrated cross section: 0
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Scattering cross section
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Isc,0 = Ia 0/ 02/
N. Pietralla et al., Phys. Rev. C, 51, 1021 (1995).
Angular Distribution, Spin Quantum Number J
Photon helicity 1, m = 1
non-isotropically alignment of
photo-excited state
(even oriented for circularly
polarized beam)
Pronounced angular correlations
when involving spin-0 states
Angular distribution functions W()
from angular correlation theory
Spin quantum numbers J
(easiest in even-even nuclei). 2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
90o/127o – intensity ratios: 2.0 (J=2) vs 0.8 (J=1)
Parity quantum number p for J=1 states
Elastic scattering distribution not isotropic about incident polarization plane.
No intensity along oscillating dipole vector
Azimuthal rotation by 90o for M1 and E1 distributions
Observable only for linearly polarized beam
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Linearly-polarized photon beam:
Parity measurement by azimuthal distribution
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
NRF – Set-up and parameters
Count rate estimate
104 /(s eV) in 100 macropulses
100 /(s eV) per macropulses
Example: 10 mg, A 200 target
Resonance width = 1 eV
2 excitations per macropulse
0.5 photons per mac.p. in detector
PP-count rate 6 Hz
1.000 counts per 3 min.
E.g. 252Cf, T1/2 = 2645 a
10 mg = 100 MBq (E=43 keV)
Backgrd. count rate 100 kHz/det.
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
8 HPGe detectors
2 rings at 90o and 127o
rel(HPGe) = 100%
Solid angle 1p
Photopeak PP 3%
Costs: 1.460 kEUR
target
HPGe
Last week‘s example: 31P
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Christopher Romig, TU Darmstadt
Data taken at HIS, 09/27/2012
50% P2O5
J=1/2
Jp=3/2+
TDR NRF – Set-up
8 HPGe detectors (100%ers, + BGO-shields, 160 kEUR each)
Frame, mechanics, cabling (100 kEUR)
HV supply, digital DAQ (50 kEUR)
LN2-supply (30 kEUR)
Total: 1.460 kEUR
Ancillary particle detectors (for (,p[‘])-reactions)
1 x 15 cm DSSD-“CD“ (8 rings x 8 sectors, backward cap, 20 kEUR)
8 x 10 x 10 cm2 DSSDs (10 x 10 strips, „target barrel“, 70 kEUR)
HV supply, digital DAQ (180 channels, 250 kEUR)
Sub-Total (ancillary-only): 340 kEUR
This will make entirely new reaction possible, partic., on isotopes with Sp < Sn
Total TDR: 1.800 kEUR, established technology, ready on day-one
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
doesn‘t make it all
Momentum transfer
ELI – NP has a superior electron
beam for nuclear structure
research (200 – 700 MeV,
E/E 10-4)
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
(,‘): d/d(E)
(e,e‘): d/d(E,q)
Virtual-photon scattering
(= electron scattering) decouples
energy and momentum transfer
Electron sensitive to form factor
charge distribution
Charge (and magnetization)
distributions sensitive observable
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Electron and Proton Scattering on A = 90
O.Burda et al., Phys.Rev.Lett. 99, 093502 (2007)
One-phonon states are strongly excited in
(e,e‘) and (p,p‘) scattering experiments
S-DALINAC data
• Typical beam current: 5 A
• 10 mg/cm2 target
• Elastic line: 20 Hz
• Total rate: 100 Hz
• E/E = 4 10-4
Experimental setup
25. Mai 2012 | Institut für Kernphysik | TU Darmstadt | Abdulrahman Scheikh Obeid | 4
Spectrometer
25. Mai 2012 | Institut für Kernphysik | TU Darmstadt | Abdulrahman Scheikh Obeid | 5
Recent example 92Zr
25. Mai 2012 | Institut für Kernphysik | TU Darmstadt | Abdulrahman Scheikh Obeid | 6
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Transition Form Factors for 92Zr
Diffraction pattern in (p,p‘) shifted to higher momentum transfers for MSS
MSS has smaller matter transition radius than FSS! p-n-phase?
C.Walz,… NP,… et al., Phys. Rev. Lett. 106, 062501 (2011)
S-DALINAC data
2. Sept. 2012 | Norbert Pietralla @ 6th Tours Symposium | Photonuclear Physics: From the S-DALINAC to ELI
Transition Form Factors for 92Zr
Diffraction pattern in (p,p‘) shifted to higher momentum transfers for MSS
MSS has smaller matter transition radius than FSS! Access p-n-phase!
C.Walz…NP… et al., Phys. Rev. Lett. 106, 062501 (2011)
S-DALINAC data
Model-independent extraction of E2 excitation
strength
< 3% negligible
Expansion in momentum transfer
25. Mai 2012 | Institut für Kernphysik | TU Darmstadt | Abdulrahman Scheikh Obeid | 9
Example: Darmstadt Q-CLAM spectrometer
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Count-rate estimate
Arguments for (e,e‘) @ ELI-NP
Complementary energy range
150 – 700 MeV
ELI-NP competitive resolution
Timing ideal for coincidences
„parasitic“ experiments easily
possible
Optimize spectrometer
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
S-DALINAC (E < 130 MeV)
Typical beam current: 5 A
10 mg/cm2 target
Elastic line: 20 Hz
Total rate: 100 Hz
E/E = 4 10-4
ELI-NP e-beam
Ie 5 A
in 100 x 1000 microbunches
On average 1 ct / macrobunch
At least < 5 cts / macrobunch
No pile-up
No deadtime
TDR (e,e‘)
Allocate space for (e,e‘) !
Evtl. optimize e-beam dump
Beam lines and valves: 130 kEUR
Scattering chamber: 50 kEUR
Pre-collection quadrupole magnet: 70 kEUR
Large-gap dipole magnet: 2 MEUR
Wire chambers for e-tracks: 400 kEUR
Cherenkov counter: 150 kEUR
Vaccum needs: 100 kEUR
DAQ: 200 kEUR
Total needs: 3.1 MEUR
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Summary
Nuclear dipole physics with -ray and e-beams is a vivid field
ELI-NP will become the ultimate NRF facility
Established technology, ready from day-one
Join the NRF@ELI-NP working group!
ELI-NP can be a highly competitive electron facility, either.
Technique fully developed: buy from the shelf
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI
Thank you !
2. July 2012 | Norbert Pietralla @ CSSP Sinaia | Physics @ ELI-NP: NRF from the S-DALINAC towards ELI