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Barney, J.

Publications and source records attributed to Barney, J..

28 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

First Observation of Unbound O 11 , the Mirror of the Halo Nucleus Li 11

The structure of the extremely proton-rich nucleus O 8 11 3 , the mirror of the two-neutron halo nucleus Li 3 11 8 , has been studied experimentally for the first time. Following two-neutron knockout reactions with a O 13 beam, the O 11 decay products were detected after two-proton emission and used to construct an invariant-mass spectrum. A broad peak of width ~ 3.4 MeV was determined. Within the Gamow coupled-channel approach, it was concluded that this peak is a multiplet with contributions from the four lowest O 11 resonant states: J π = 3 / 2 1 - , 3 / 2 2 - , 5 / 2 1 + , and 5 / 2 2 + . The widths and configurations of these states show strong, nonmonotonic dependencies on the depth of the p - C 9 potential. This unusual behavior is due to the presence of a broad threshold resonant state in N 10 , which is an analog of the virtual state in Li 10 in the presence of the Coulomb potential. After optimizing the model to the data, only a moderate isospin asymmetry between ground states of O 11 and Li 11 was discovered.

6 ≤ A ≤ 19↗
DOE OSTI2019

Non-linearity effects on the light-output calibration of light charged particles in CsI(Tl) scintillator crystals

The light output produced by light ions ( Z ≤ 4) in Csl(Tl) crystals is studied over a wide range of detected energies (E ≤ 300 MeV). Energy-light calibration data sets are obtained with the 10 cm crystals in the recently upgraded High-Resolution Array (HiRA10). We use proton recoil data from 40,48 Ca + CH 2 at 28 MeV/u, 56.6 MeV/u, 39 MeV/u and 139.8 MeV/u and data from a dedicated experiment with direct low-energy beams. We also use the punch through points of p, d, and t particles from 40,48 Ca + 56,64 Ni, 112,124 Sn collisions reactions at 139.8 MeV/u. Non-linearities, arising in particular from Tl doping and light collection effects in the CsI crystals, are found to significantly affect the light output and therefore the calibration of the detector response for light charged particles, especially the hydrogen isotopes. A new empirical parametrization of the hydrogen light output, $L(E,Z=1,A)$, is proposed to account for the observed effects. Results are found to be consistent for all 48 CsI(Tl) crystals in a cluster of 12 HiRA10 telescopes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Application of the Generic Electronics for Time Projection Chamber ($\mathrm{GET}$) readout system for heavy Radioactive isotope collision experiments

Here we have implemented the Generic Electronics for Time Projection Chamber (GET) in a SAMURAI Pion Reconstruction and Ion-Tracker (SπRIT) readout system for heavy radioactive ion collision experiments at RIKEN-RIBF. The SπRIT experiment is designed for heavy ion collision experiments with radioactive ion beams, where a Time Projection Chamber (TPC) with 12096 pixelized readout pads is employed as the main device. Since the TPC is located on the beam line, the readout electronics must handle small signals from pions as well as very large signals from beam or large fragment particles. Operation of the GET electronics during experiment functioned well using 270 time-bucket readout with 25 MHz sampling at an event Data acquisition (DAQ) rate of 60 Hz. Using the slope information of acquired signals it is possible to extend the dynamic range of dE/dx information compared to using the peak height information. However, huge signals arising from energetic δ-rays produced by un-interacted projectiles induce dead channels, which can be recovered after 70 μs on average.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Pion production in rare-isotope collisions

Pion energy spectra are presented for central collisions of neutron-rich 132 Sn + 124 Sn and neutron-deficient 108 Sn + 112 Sn systems using simulations with the Boltzmann-Uehling-Uhlenbeck transport model. These calculations, which incorporate isospin-dependent mean-field potentials for relevant baryons and mesons, display a sensitivity to the pion spectra that could allow significant constraints on the density dependence of the symmetry energy and its mean-field potential at suprasaturation densities. As a result, the predicted sensitivity increases with the isospin asymmetry of the total system and decreases with incident energy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

KATANA – A charge-sensitive triggering system for the SπRIT experiment

KATANA - the Krakow Array for Triggering with Amplitude discrimiNAtion - has been built and used as a trigger and veto detector for the SπRIT TPC at RIKEN. Its construction allows operating in magnetic field and providing fast response for ionizing particles, giving an approximate forward multiplicity and charge information. Depending on this information, trigger and veto signals are generated. The article presents performance of the detector and details of its construction. A simple phenomenological parametrization of the number of emitted scintillation photons in plastic scintillator is proposed. The effect of the light output deterioration in the plastic scintillator due to the in-beam irradiation is discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

A gating grid driver for time projection chambers

A simple but novel driver system has been developed to operate the wire gating grid of a Time Projection Chamber (TPC). This system connects the wires of the gating grid to its driver via low impedance transmission lines. When the gating grid is open, all wires have the same voltage allowing drift electrons, produced by the ionization of the detector gas molecules, to pass through to the anode wires. When the grid is closed, the wires have alternating higher and lower voltages causing the drift electrons to terminate at the more positive wires. Rapid opening of the gating grid with low pickup noise is achieved by quickly shorting the positive and negative wires to attain the average bias potential with N-type and P-type MOSFET switches. The circuit analysis and simulation software SPICE shows that the driver restores the gating grid voltage to 90% of the opening voltage in less than 0.20 µs, for small values of the termination resistors. When tested in the experimental environment of a time projection chamber larger termination resistors were chosen so that the driver opens the gating grid in 0.35 µs. In each case, opening time is basically characterized by the RC constant given by the resistance of the switches and terminating resistors and the capacitance of the gating grid and its transmission line. By adding a second pair of N-type and P-type MOSFET switches, the gating grid is closed by restoring 99% of the original charges to the wires within 3 µs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1984

Detecting Defective Solder Bonds

Method is noncontact and nondestructive. Technique detects solder bonds in solar array of other large circuit board, using thermal-imaging camera. Board placed between heat lamp and camera. Poor joints indiated by "cold" spots on the infrared image.

Paulson, R.↗