Soft collective excitations in weakly bound nuclei studied with ELI-NP
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Transcript of Soft collective excitations in weakly bound nuclei studied with ELI-NP
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Soft collective excitations in weakly bound nuclei studied with ELI-NP
A.Krasznahorkay
Inst. of Nuclear Research of the Hung. Acad. of Sci. (ATOMKI)
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ELI Attosecond Light Pulse Source
1) To generate X-UV and X-ray fs and atto pulses, … ATTOSECOND section
2) To contribute to the technological development towards 200PW… High-intensity section
Attosecond Beamline
THZ & appl.Gas HHG:
Atto & XUVApplications
OPA chain / stagesCW DPSSL pump
50 mJ / 10 kHz
1J / 1 kHz Solid HHG:Atto & X-Ray
SynchronizedAtto/PW Facility
PW applications
10 mJ / 10 kHz @ mid-IR
10 PW/ 300J/ 0.1HzHigh-intensity Beamline
OPA chain / stages I-VIPulsed DPSSL pump
Ti:SapphireFlashlamps
5 J / 10 Hz
1J / 100Hz
2x Oscillator+ front end
10 kHz
Attosecond Beamline
THZ & appl.Gas HHG:
Atto & XUVApplications
OPA chain / stagesCW DPSSL pump
50 mJ / 10 kHz
1J / 1 kHz Solid HHG:Atto & X-Ray
SynchronizedAtto/PW Facility
PW applications
10 mJ / 10 kHz @ mid-IR
10 PW/ 300J/ 0.1HzHigh-intensity Beamline
OPA chain / stages I-VIPulsed DPSSL pump
Ti:SapphireFlashlamps
5 J / 10 Hz
1J / 100Hz
2x Oscillator+ front end
10 kHz
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1. High resolution study of the soft dipole resonances
2. Determination of the strengths of the pigmy dipole resonances
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Grand Raiden with complete dispersion matching techniques. The relative energy resolution is the best in the world (ΔE/E ≈ 10-5 ).
The spectrometer was set at 0° and 2.5° with an opening angle of ±20 mrad horizontally and ±20 mrad vertically defined by a slit at the entrance of the spectrometer.
Research Center for Nuclear Physics (RCNP), Osaka University.(3He,t) charge exchange reaction.400 MeV 3He on 40Ca, 42Ca, 44Ca and 48Ca targets.
Previus experiment
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We determined the precise level energies for each isotopes and deduced their intensities by fitting the energy spectra.
Identification of new excited states
Energy (MeV)
Counts
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Angular distributions
ϴ (deg.)
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Low-lying dipole strengths
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Super fluid vibrations?Alpha condensate?
B. Cederwall et al., Nature 469, 68-71 (2011)
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RPA calculations
• The theoretical description (RPA of the distribution is in progress (Elena Litvinova, GSI)
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Theoretical description (RPA) Elena Litvinova, GSI
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Comparison of the experimental and theoretical results
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A new step with ELI-NP
• Pure electromagnetic probe for exciting exclusively the dipole strengths
• γ-beam combined with the chrystal spectrometer (GAMS4 from ILL Grenoble)
• Ultimately high energy resolution (ppm) allows to measure the natural widths (Γ) of the levels and determine the absolute strengths for a large number of transitions for the first time!
• A new experimental window will be opened to discover new phenomena in nuclear structure physics!
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Constraining the symmetry energy of the EoS by precise neutron-skin thickness measurements
Accepted SIS18 experiment (S408), Spokeperson: A. Krasznahorkay
Furnstahl, Nucl. Phys. A706 (2002) 85
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The symmetry energy in nuclear matter
...0,, 42 OSEE
...),(
2
1)( 02
0
0402
2
pa
ES
A
ZN
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Dipole strengths exited in (p,n) reactions in inverse kinematics
pnGDRGDR rZrNSS 22
2
9
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Study of pigmy resonances
Constraints on the symmetry energy and neutron skins from pygmy resonances in 68Ni and 132Sn (PRC 81, 041301(R) (2010))
S(ρ)|ρ=ρ0 = L/3ρ0
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Experimental requirements
• High resolution (10-6) tunable photon beam
• Detectors with very high counting rate capabilities
• Flesh ADCs with high (1-2 GHz) sampling rate
• Good collimators and very well shielded beam dump
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The GAMS4 flat crystal facility (E.G. Keller et al., NIM A457 (2001) 187.)
Michael Jentschel
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Advantages of LaBr3 scintillators
• Best energy resolution
• Fast emission
• High count rate capabilities
• Excellent radiation hardness
• Wavelength of emission max. [nm] 380
• Primary decay time [ns] 16
• Light yield [% of NaI(Tl)] (for γ-rays) 165
M. Ciemala., … A. Krasznahorkay et al., NIM A608 (2009) 76.Fast anti-coincidence shield is
needed to get better response at high energy !!!
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Energy resolution and efficiency
Typical time resolution: 250 ps (for large detectors)Spacial resolution <80 cm !!!Scattered background could be reduced
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Experimental arrangement
E7 8x8 m
E8 5x8 m
GAMS 4 3x4 m
Shilded beam dump
4 pcs of 3”x3” AC LaBr2 detectors
Cost estimates for detectors: 4x40 k€+ acquisition system: ~ 40 k€
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Thank you for your attention