Exotic Nuclear Matter Research Articles

A Development of a 40-Gb/s Readout Interface STARE for the AGATA Project

The Advanced GAmma Tracking Array (AGATA) multidetector spectrometer will provide precise information for the study of the properties of the exotic nuclear matter (very unbalanced proton (Z) and neutron (N) numbers) along proton- and neutron-drip lines and of super-heavy nuclei. This is done using the latest technology of particle accelerators. The AGATA spectrometer consists of 180 high-purity germanium detectors. Each detector is segmented into 38 segments. The very harsh project requirements are to measure gamma-ray energies with very high resolution ( <; 1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> ) at a high detector counting rate (50 K events/s/crystal). This results in a very high data transfer rate per crystal (5-8 Gb/s). The 38 segments are sampled at 100 MHz with 14 bits of resolution. The samples are continuously transferred to the control and processing (CAP) module, which reduces the data rate from 64 to 5 Gb/s. The CAP module also adds continuous monitoring data, which results in total outgoing data rate of 10 Gb/s. The serial transfer acquisition and readout over Ethernet (STARE) module is designed to fit between the CAP module and the computer farm. It will package the data from the CAP module and transmit it to the server farm using a 10-Gb/s user datagram protocol (UDP) connection with a delivery insurance mechanism implemented to ensure that all data are transferred.

Isobaric charge-exchange reactions: a tool to study the excitation of baryonic resonances in exotic nuclear matter

Isobaric charge-exchange reactions induced by beams of 112Sn have been investigated at the GSI facility using the fragment separator FRS. The high-resolving power of this spectrometer makes it possible to obtain the isobaric charge-exchange cross sections with an uncertainty of 3.5% and to separate quasi-elastic and inelastic contributions in the missing-energy spectra, in which the inelastic component is associated to the in-medium excitation of baryonic resonances such as the Δ resonance. We report on the results obtained for the (p,n) channel excited by using different targets that cover a large range in neutron excess. In addition, we also compare the missing-energy spectra with an intranuclear cascade model coupled to a de-excitation code to investigate the in-medium effects in the production of baryonic resonances.

Approaching the Island of Stability --- Walking on Firm Grounds

The research in the field of superheavy elements started in the sixties of the last century triggered by the prediction of a region of enhanced nuclear stability at the next closed proton and neutron shells beyond 208Pb. Adam Sobiczewski was one of the first predicting proton and neutron numbers for these shell closures at Z = 114 and N = 184, respectively. In the following decades, extensive efforts led to the synthesis of isotopes of elements up to Z = 118 in a fruitful competition of the leading laboratories in the field with FLNR/JINR in Dubna, Russia, LBNL in Berkeley, USA, GSI in Darmstadt, Germany and most recently RIKEN in Wako (Tokyo), Japan. Beyond the synthesis of new elements and isotopes, substantial activities were dedicated to nuclear structure studies, laying the basis for the understanding of this exotic nuclear matter. In-beam spectroscopy as well as decay spectroscopy after separation (DSAS) together with the support by theory have the potential to lay the basis for a successful approach of the so-called island of stability, the firm grounds, the creation of which had been started by pioneers like Adam Sobiczewski in the beginning of the second half of last century. In this paper, some of the achievements mainly of DSAS will be presented, with an emphasis on the guidance by theory and the work of Adam Sobiczewski, to whom this paper is dedicated.

Exotic nuclear matter

Recent developments of nuclear structure theory for exotic nuclei are addressed. The inclusion of hyperons and nucleon resonances is discussed. Nuclear multipole response functions, hyperon interactions in infinite matter and in neutron stars and theoretical aspects of excitations of nucleon resonances in nuclei are discussed.

Search for Eta-mesic Helium via Deuteron–Deuteron Reactions with the WASA-at-COSY Facility

The -mesic nuclei in which the meson is bound with nucleus via strong interaction was postulated already in 1986, however till now no experiment conrmed empirically its existence. The discovery of this new kind of an exotic nuclear matter would be very important for better understanding of the meson structure and its interaction with nucleons. The search for -mesic helium is carried out with high statistic and high acceptance with the WASA-at-COSY detection setup in the Forschungszentrum

Search for the He-[formula omitted] bound states with the WASA-at-COSY facility

The existence of η-mesic nuclei in which the η meson is bound with nucleus by means of the strong interaction was postulated already in 1986, however till now no experiment confirmed it empirically. Discovering of this new kind of an exotic nuclear matter would be very important as it might allow for better understanding of the η meson structure and its interaction with nucleons. The search for η-mesic helium (4He-η) is carried out with high statistic and high acceptance by means of the WASA detector, installed at the cooler synchrotron COSY in the Research Center Jülich. The search is conducted via the measurement of the excitation function for the chosen decay channels of the 4He-η system. In the experiment performed in November 2010 two reactions dd→(4He -η)bs→3Hepπ− and dd→(4He -η)bs→3Henπ0 were measured with the beam momentum ramped from 2.127 GeV/c to 2.422 GeV/c. The report includes the description of experimental method and status of the measurement.

Search for the He-ηbound states with the WASA-at-COSY facility

The eta-mesic nuclei in which the {\eta} meson is bound with nucleus via strong interaction was postulated already in 1986, however till now no experiment confirmed empirically its existence. The discovery of this new kind of an exotic nuclear matter would be very important for better understanding of the {\eta} meson structure and its interaction with nucleons. The search for {\eta}-mesic helium is carried out with high statistic and high acceptance with the WASA-at-COSY detection setup in the Research Center Juelich. The search is conducted via the measurement of the excitation function for the chosen decay channels of the 4He-{\eta} system. Till now two reactions dd --> (4He-{\eta})_bs --> 3Hep\pi- and dd --> (4He-{\eta})_bs --> 3 Hen{\pi}0 were measured with the beam momentum ramped around the eta production threshold. This report includes the description of experimental method and status of the analysis.

Modern Rutherford Experiment: Tunneling of the Most Neutron-Rich Nucleus

A modern variation of the Rutherford experiment to probe the tunneling of exotic nuclear matter from the measurement of the residues formed in the bombardment of (197)Au by extremely neutron-rich (8)He nuclei is presented. Using a novel off-beam technique the most precise and accurate measurements of fusion and neutron transfer involving reaccelerated unstable beams are reported. The results show unusual behavior of the tunneling of (8)He compared to that for lighter helium isotopes, highlighting the role of the intrinsic structure of composite many-body quantum systems and pairing correlations.

Experimental constraints on strangelets and other exotic nuclear matter

A reanalysis of data from a recent search for ultraheavy isotopes of gold and iron leads to new constraints on several classes of exotic objects. These include strangelets, MEMOs (metastable exotic multihypernuclear objects), and CHAMPs (charged massive particles) which may have been present in the data, but which could have nonetheless gone undetected due to the design of the original experiment. As a result of the new analysis we are able to greatly enlarge the exclusion regions for exotic particles of mass M and charge Z, and provide limits as low as ${10}^{\ensuremath{-}11}$ for small $M/Z,$ and ${10}^{\ensuremath{-}7}$ for $M/Z$ up to 120.

Towards exotic nuclear matter

In this article I would like to describe what I am doing right now. First, introductory remarks on nuclear matter at high densities and/or high temperatures are presented. Then, I report our recent data obtained at the Brookhaven AGS. Finally, I describe briefly our future RHIC experiment, PHENIX.