Session SC: Instrumentation II

ND-Cube: An active-target detector for radioactive beam experiments and detector development

Active-target detectors have enabled the studies that can take advantage of their tracking capabilities and include studies with radioactive beams and reactions with low-energy decay products. We have developed an active-target detector, the ND-Cube, to enable such studies at the Nuclear Science Laboratory at the University of Notre Dame. The ND-Cube has a rectangular geometry that has an active volume of approximately 19 x 25 cm$^2$ and currently uses a Micromegas micropattern gas detector for electron amplification and detection. GET electronics are used for the read-out electronics. The ND-Cube will also be used as a platform for the development of active-target detector features and characterization such as \textit{in situ} drift velocity measurements and space charge characterization. The ND-Cube is also unique in that the majority of its components were designed and built by undergraduate researchers. The first test measurements with the ND-Cube will be presented as well as its first planned science measurements using radioactive beams.   

Design, Simulation and Construction of MuSIC@Indiana

Fusion of neutron-rich nuclei is presently a topic of considerable interest. The most neutron-rich beams delivered by radioactive beam facilities however are typically available only at low intensities (\textless 1000 ions/s). At energies above the fusion barrier, a \textbf{Mu}ltiple \textbf{S}ampling \textbf{I}onization \textbf{C}hamber (\textbf{MuSIC}) acting as an active target provides an effective means of measuring the fusion excitation function with such low-intensity beams. The advantages and limitations of this approach will be discussed. The design, construction and initial testing of MuSIC@Indiana will be detailed. Simulations of the detector performance will be described and initial preparations to measure fusion of $^{\mathrm{19,20,21}}$O $+ \quad^{\mathrm{12}}$C will be summarized.   

Characterization of a low background counting facility at the Kimballton Underground Research Facility

We report on the characterization of a new low-background counting setup at the Kimballton Underground Research Facility in Virginia. The facility consists of a shielded, high-purity germanium detector deployed at a depth of approximately 300 meters water equivalent and equipped with a muon veto system. Exploiting gamma ray spectroscopy in a low cosmic-ray flux environment the facility can be used to screen materials for applications in low-background experiments, such as neutrinoless double-beta decay or dark matter searches. We present the efficiency of the detector calculated using a GEANT4 simulation, and the sensitivity to isotopes of common interest — $^{238}$U, $^{232}$Th and $^{40}$K. As the background goals in next-generation rare decay searches become ever-more stringent, high-sensitivity radiopurity screening facilities will continue to play an important role supporting this science.   

Charged Particle Detector Telescope for Studies of Neutron-rich Systems

A straight-forward type of experiment on neutron-rich systems involves detecting a single neutron and charged particle resulting from a nuclide decaying from a neutron-unbound state. However the charged fragment may be in a bound excited state resulting in gamma-ray emission, such as for some neutron-unbound states of $^{\mathrm{25}}$F and $^{\mathrm{13}}$Be. Thus efficient coincident detection of gamma-rays, neutrons, and charged particles is desired. A compact charged particle detector telescope design is being developed to provide detection of charged particles, allow the neutron to pass through with minimal attenuation to then be detected by the MoNA-LISA, and allow gamma-ray detection. Charged particles resulting from neutron-emission will pass through one silicon position sensitive detector (140$\mu$m thick) and a stack of silicon detectors (500$\mu$m thick) with a CsI crystal (3 cm thick) read out by a silicon photomultiplier (SiPM). An additional silicon position sensitive detector at the reaction target will provide the position information to calculate charged particle trajectories. This system will be installed at the NSCL and will also be available for use at FRIB. This talk will discuss initial testing of system components and the experimental setup.   

Precise Calibration of Laser Frequency for determination Sc Charge Radii

A kink structure is observed at the magic numbers in chains of charge radii but is missing at the neutron number $N \quad =$ 20 for $_{\mathrm{18}}$Ar, $_{\mathrm{19}}$K and $_{\mathrm{20}}$Ca. Determination of the charge radii of proton-rich $_{\mathrm{21}}$Sc isotopes across $N \quad =$ 20 are planned to address the disappearance of shell-closure signature. Collinear laser spectroscopy, which requires accurate and precise knowledge of laser frequency, will be used to deduce the charge radii. To calibrate the laser frequency, a Doppler-free spectroscopic measurement of molecular iodine is being implemented to measure precisely-known transitions in the visible to near-infrared wavelength region. The status of development and test results will be discussed.   

Application of experimental methods of nuclear physics for studies of fundamental quantum physics

In nuclear physics arrays of silicon drift detectors (SDDs) are extremely successful detectors for the spectroscopy of X-ray transitions in kaonic atoms. New experiments using X-ray spectroscopy at DAFNE/LNF-INFN in Italy and J-PARC in Japan for the first strong interaction studies of the exotic atom, kaonic deuterium, are in preparation. The development of SDD X-ray detectors is also essential part of present experiments in the foundation of quantum physics, like testing the spin statistics for electrons. The experiment VIP2 at the underground laboratory Gran Sasso is using the same kind of solid-state detectors for precision X-ray detection. In the talk an overview of application of SDDs in nuclear physics at DAFNE and J-PARC employing kaonic atoms will be given.   

Electron Population Manipulation of Transition Metal Isotopes in an RFQ Ion Trap

Collinear laser spectroscopy(CLS) is a powerful tool for determining the differential mean-square charge radii and nuclear electromagnetic moments of rare isotopes. CLS measurements of the first and second-row transition metals are difficult due to low production rates and unfavorable electronic populations. An optical pumping technique has been developed at the BECOLA facility at the NSCL/MSU to manipulate electronic populations and improve sensitivity in laser spectroscopy measurements. The technique was tested with stable Zr beams, whose neutron-deficient isotopes have important implications for stewardship science. A $^{90}$Zr ion beam was produced in a plasma discharge source and trapped in an RFQ ion trap. The electronic populations of the trapped ions were manipulated with pulsed laser light followed by laser-resonant fluorescence measurements. Details and results from commissioning tests will be discussed.   

Neutron Spectroscopy Studies with the CATRiNA Detector System

Experimental studies of exotic neutron-rich and neutron-deficient nuclei are becoming available due to the emergence of advanced radioactive beam facilities. New neutron detection systems are in need to study nuclear reactions with these exotic nuclei which involve neutrons as reaction by-products. Neutron detection arrays should be capable of performing neutron spectroscopy studies and using neutrons to 'tag' other by-products (e.g. γ-ray, α-particle). The Compound Array for Transfer Reactions in Nuclear Astrophysics (CATRiNA), developed at Florida State University (FSU), is an array of 16 deuterated-benzene (C6D6) scintillators as neutron detectors with fast-response time, pulse-shape-discrimination capabilities and a structured pulse-height spectrum which combined with time-of-flight (ToF) information, allows for multiple correlations for neutron spectroscopy studies. CATRiNA was designed to perform spectroscopy studies of bound- and resonant-states and to be coupled with other detection systems to measure reactions relevant for nuclear structure and nuclear astrophysics. In this work, we will discuss preliminary results on experiments performed at FSU.   

Fusion measurements of exotic beams with "Encore", the new Active Target Detector at FSU

Exotic nuclei and beams are on the forefront of nuclear science and with them, new detector systems to exploit these beams to their greatest extent. These radioactive beams allow the measurement of new exotic fusion systems which,will in turn help understand fusion processes near the coulomb barrier as well as energy production within stars. At Florida State University (FSU) we have developed 'Encore', a Multi Sampling Ionization Chamber which works as an active target detector consisting of a segmented anode to measure energy losses of the beams and the subsequent reactions as the beam passes through the detector. preliminary Results on the characterization of the detector, future improvements and first measurements of the 17 F $+$ 12 C system performed at FSU using a radioactive 17 F beam will be presented This work was supported by the State of Florida and the NSF under grant PHY-1712953   

Gas-production reaction studies: 54Fe(N,Z) measurements with LENZ at LANSCE

The development of the LENZ (Low Energy NZ-neutron induced charged particle detection) set-up at LANSCE gives the capability of studying neutron induced reactions in detail. The wide neutron spectrum of LANSCE, in addition to the large solid angle coverage of LENZ, provides a unique tool for the disentanglement of the excited states. In addition, it improves the information we have up to now, giving the angular distribution of the different channels as well as information useful on statistical models such as Hauser-Feshbach used for many neutron induced reactions. Fe is one of the mostly used structural materials. Its importance lies not only in applications but also in nuclear astrophysics. The total and differential cross sections, as well as angular distributions of the $^{54}$Fe(n,p) reaction will be presented and compared with recent evaluations. This benchmark study will aid the ongoing analysis and evaluation of multiple reaction measurements in the LENZ project, including on radioactive isotopes.