Nuclear resonance fluorescence (NRF) experiments provide a specific research niche for the ELI-NP facility.
In particular, the pencil-size gamma beams at ELI-NP will provide access to targets that are available in small quantities and will open the actinide region for NRF studies.
Detailed high-resolution studies of the dipole strength distribution in the region of the pygmy dipole resonance (PDR) will be done.
Related to this experimental program, the ELIADE detector array of segmented Ge Clover detectors and digital read-out is under construction:
The ELIADE (ELI-NP Array of DEtectors) is composed of 8 segmented clover HPGe detectors and additional 4 LaBr3 detectors.
The detectors are located on two rings, one at 90 degrees and the other at 135 degrees with respect to the beam axis.
The angle of the detectors in the first ring can be varied with 4 degrees around the nominal working position.
[Romanian Reports in Physics, Vol. 68, Supplement, P. S483–S538, 2016]
Experiments above the neutron threshold address open questions related to nuclear structure and astrophysical abundances of nuclear species,
e.g. photodisintegration cross-sections for low-abundance nuclei relevant to the p-process nuclear synthesis, and nuclear structure
of the giant dipole resonances (GDR) from studies of gamma and neutron decays, as well as studies of the pygmy-dipole resonance (PDR)
and the magnetic dipole resonance (MDR), appearing as excess strength at the lower-energy tail of the GDR, will be performed.
In addition, resolution of the large literature discrepancies of the partial (γ,xn) cross-sections with improved measurements
will be done. In particular two main configuration are under construction related to this experimental program: ELIGANT-GN and
The current configuration of ELIGANT-GN has 15 LaBr3(Ce) and 19 CeBr3 scintillator detectors for gamma-ray detection, and 33 liquid and
22 Li-glass scintillator detectors for fast-neutron detection. The main goal of ELIGANT-GN is to detect coincidences between gamma rays
and neutrons emitted by de-exciting nuclei.
The current configuration of ELIGANT-TN consists of 28 helium-3 tubes embedded in a polyethilene cube.
Experiments in the field of photofission address mapping of the fission barriers through studies of transmission fission resonances,
as well as studies of rare fission modes. For the realization of this experimental programme two instruments are designed:
The ELI-BIC (Bragg Ionization Chamber) is an assembly of four chambers, each of which contains one high-eﬃcient double-sided
Frisch-grid ionization chamber for the detection of binary fission fragments together with eight ∆E-E telescopes to measure light charged particles.
Each telescope consists of an ionization chamber and a double-sided silicon strip detector (DSSD) to determine energy loss and remaining energy, respectively.
As counting gas, P-10 (90% argon, 10% methane) at around 1 bar will be used.
ELITHGEM consists of 12 detectors of THGEM (THick Gas Electron Multiplier) type, which offer position sensitivity as well as high gain.
The entire detector covers a solid angle of around 80% of 4π and each THGEM unit, together with a segmented readout electrode, provides a true pixelated radiation localization
with an angular resolution of about 5°. The array is contained inside a gas chamber, filled with isobutane gas at a pressure of around 5 mbar.
At ELI-NP we develop a research program for studies of the structure of exotic nuclei.
The nuclei of interest will be produced by photofission of actinide nuclei by a broad-bandwidth gamma beam,
covering the region of the giant dipole resonances (GDR).
The ELISOL facility will produce radioactive ion beams (RIBs) via photofission in a stack of actinide targets
placed at the center of a gas cell. This Cryogenic Stopping Cell (CSC) will operate with helium at around 75K and will employ diverse DC and RF electric fields
to thermalize and drift out quickly the fission fragments. A Radio-Frequency Quadrupole (RFQ) will form the RIBs by cooling, bunching and mass filtering these fragments.
The exotic neutron-rich component of the RIBs will be selected by a Multiple Reflection Time-of-Flight (MR-ToF) mass spectrometer with high resolving power.
Finally, the selected rare and exotic nuclei will be analyzed by a beta-decay tape station and a collinear laser spectroscopy station.
The Extreme Light Infrastructure Silicon Strip Array (ELISSA) is a new silicon-strip detector array under construction at ELI-NP.
Several reactions important for the astrophysical p-process, Big Bang Nucleosynthesis and supernova explosion have been selected for
the first measurement campaigns.
One of the key reactions to measure is the 7Li(γ,3H)4He which is of interest for the longstanding "Cosmological Li problem" and for verifying several recent
theoretical predictions. Measurements at γ-ray energies above 3.5 MeV with ELISSA could restrict the extrapolation of the cross section
to astrophysically important energies.
Photodissociation processes are among the most important nuclear reactions during p-process nucleosynthesis. Several p-nuclei of Mo and Ru are produced only
by the p-process in supernova explosions. Measurements of (γ,p) and (γ,4He) on 92Mo, 96Mo and 98Ru, and
144 and 146Sm are proposed with ELISSA.
The ELISSA design consists of X3 position-sensitive silicon-strip detectors arranged in three rings of 12 detectors in a barrel configuration and 8 annular silicon-strip detectors covering the end-caps.
ELISSA provides charged particle detection with low thresholds, high energy and angular resolution over an almost 4π solid angle.
The ELI Time Projection Chamber (ELITPC) is a gaseous detector in which the gas acts at the same time as a target for the nuclear reaction and detection medium.
The detector will be used to investigate the multi alpha-particle decay of light nuclei such as 12C and 16O and the cross section of photo-dissociation reactions
(γ,p) or (γ,α). The active volume of the chamber, in which the reaction happens and the decay products are detected, will have a length of 35 cm and a square
cross-section of 20 cm × 20 cm, centred around the beam axis with a window for the gamma beam and another on the side for an alpha source. The multiplication of
the drifting electrons will be achieved by a sequence of 35 cm × 20 cm Gas Electron Multiplier (GEM) foils. The charge will be read by a u-v-w readout which is
mounted on a circuit board using multi-layering board technology and it is formed by three layers of (u-v-w) grids crossedat 60°. Combination of the 2D position
in the collection plane with time information will allow the 3D reconstruction of the reaction products. The 3D reconstruction of events will also allowus to
identify reactions in which more than two particles are involved, like 12C(γ,3α), or when more events (including background) happen within a short time-window
of the information collection.
ELI-NP γ beams will be used to produce intense beams of positrons. The positron beams will be utilized for material research and characterization,
for structural and defect studies of metals, semi-conductors and insulators. Accordingly, several analytical techniques will be used and
further developed. Once circularly polarized gamma beams become available at ELI-NP, they will be used to produce polarized positron beams.
Thus, ELI-NP will offer positron beams with unprecedented capabilities.
Nuclear resonance fluorescence (NRF) analytical techniques and γ-ray based radiography and tomography will be developed at ELI-NP.
These studies will be directed towards specific nuclear non-proliferation and waste-management applications, as well as cultural
heritage research. In addition, research related to the production of radioisotopes for medical applications will be carried out
ELI-NP. For this purpose an irradiation station, combined with a pneumatic transport system and a detection system, is designed.
The detectors and spectroscopy laboratory is equipped to provide the possibility of testing detectors and electronics
setups before they are used in the designated experimental programs.