Soft collective excitations in weakly bound nuclei studied with ELI-NP A.Krasznahorkay Inst. of...

Soft collective excitations in weakly bound nuclei studied with ELI-NP

A.Krasznahorkay

Inst. of Nuclear Research of the Hung. Acad. of Sci. (ATOMKI)

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

1. High resolution study of the soft dipole resonances

2. Determination of the strengths of the pigmy dipole resonances

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

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

Angular distributions

ϴ (deg.)

Low-lying dipole strengths

Super fluid vibrations?Alpha condensate?

B. Cederwall et al., Nature 469, 68-71 (2011)

RPA calculations

• The theoretical description (RPA of the distribution is in progress (Elena Litvinova, GSI)

Theoretical description (RPA) Elena Litvinova, GSI

Comparison of the experimental and theoretical results

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!

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

The symmetry energy in nuclear matter

...0,, 42 OSEE

...),(

2

1)( 02

0

0402

2

pa

ES

A

ZN

Dipole strengths exited in (p,n) reactions in inverse kinematics

pnGDRGDR rZrNSS 22

2

9

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

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

The GAMS4 flat crystal facility (E.G. Keller et al., NIM A457 (2001) 187.)

Michael Jentschel

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 !!!

Energy resolution and efficiency

Typical time resolution: 250 ps (for large detectors)Spacial resolution <80 cm !!!Scattered background could be reduced

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€

Thank you for your attention