Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session DH: Mini-Symposium: Active Target Techniques for Studies with Exotic Beams |
Hide Abstracts |
Chair: Andrew Rogers, University of Massachusetts, Lowell Room: Hilton Kona 2/3 |
Thursday, October 25, 2018 9:00AM - 9:30AM |
DH.00001: Active Target Techniques in Low-Energy Nuclear Physics Invited Speaker: Yassid Ayyad Time Projection Chambers operated in Active Target mode have gained much attention in recent years due to their compelling tracking capabilities well suited for studying reactions with very exotic nuclei. Active targets provide high luminosity without loss of resolution, low-energy detection thresholds and enable experiments where the beam intensities can be as low as 102 pps. Because of these reasons, many facilities focused on the production of the most exotic nuclear species (i.e. FRIB (USA), RIKEN (Japan) and FAIR (Germany)) are including Active Targets in their broad and competitive experimental programs. Study of giant resonances through inelastic scattering or the investigation of cluster structures in exotic nuclei via resonant scattering are typical examples of inverse kinematic experiments that greatly benefit from the implementation of the AT technology. In this talk, I will present the evolution and application of the Active Target technology and associated techniques in low-energy nuclear physics experiments. I will begin with an overview of different Active Target detectors featuring different geometries and capabilities, and I will discuss the challenges associated with the construction of the device, the electronics and the data analysis. Finally, I will introduce the physics cases that have been studied and proposed, experiments using unconventional techniques and future projects within a broader context. |
Thursday, October 25, 2018 9:30AM - 9:45AM |
DH.00002: Encore: An Active Target Detector for measurements of Fusion Reactions. Benjamin W Asher, Sergio J Almaraz-Calderon, Lagy T Baby, Jesus Perello, Nathan Gerken Beams of Exotic nuclei are on the forefront of nuclear science due to the development of new experimental facilities around the world. With them, new detector systems are needed to exploit these beams to their greatest extent. Measuring fusion excitation functions of systems involving these exotic beams near the coulomb barrier will help understand fusion dynamics process, probe theoretical developments as well as energy production within stars. At Florida State University, we have developed Encore, a MUSIC-type detector which is a Multi Sampling Ionization Chamber working as an active target detector. Encore is based on the MUSIC detector at ANL. Its main detection principle consists of a segmented anode which measures the energy loss of a beam and the subsequent reactions as it travels through the detector. This allows measurements of reactions in a wide range of energies that depend on the initial beam energy and gas pressure inside the detector. Results on the characterization of this detector and preliminary results of first measurements will be presented. |
Thursday, October 25, 2018 9:45AM - 10:00AM |
DH.00003: Structure Studies with Low-energy Radioactive Beams from TwinSol: Resonant scattering and (α,n) reactions using Active Targets Tan Ahn, Sebastian Aguilar, Yassid Ayyad, Daniel W Bardayan, Daniel Bazin, Joshua W Bradt, Maxime Brodeur, Lisa Carpenter, Marco Cortesi, Bryce Frentz, Samuel L Henderson, William Jackson, James J Kolata, Jacob Long, Wolfgang Mittig, Patrick D O'Malley, Maxime Renaud, Michael Z. Serikow, Sabrina Y Strauss, Aidan Tollefson Various emergent structures such as clustering in light unstable nuclei can have a great influence on reaction observables such as resonant scattering, (α,n) and radiative capture reactions. At the University of Notre Dame., we use TwinSol, a pair of superconducting solenoids to produce a number of light radioactive beams to study such reactions in conjunction with active target detectors. This allows for the measurement of cross sections with low beam rates and outgoing particles with low energies. We will present the search for cluster structure in light unstable nuclei in 14O using resonant alpha scattering. This includes results of the resonant scattering analysis and future work to extend this analysis to study (α,n) reactions, which may have an influence on light-element radiative capture cross sections that are important for the production seed nuclei in various r-process scenarios. The possibility of measuring radiative capture cross sections directly will also be presented. |
Thursday, October 25, 2018 10:00AM - 10:15AM |
DH.00004: A New Experiment to Search for the Alpha Condensed State in 24Mg with MAIKo TPC Kento Inaba, Takahiro Kawabata, Tatsuya Furuno, Motoki Murata Recently, exotic low-density states, which is called αcondensed states, have been suggested to emerge near the nα-decay thresholds in self-conjugate A = 4n nuclei. These αcondensed states are expected to give an insight into the low-density nuclear matter. The αcondensed states are considered to decay by emitting multiple low-energy αparticles, reflecting their exotic structures. We plan to search for the αcondensed states in 24Mg by detecting multiple low-energy decay αparticles with MAIKo-TPC. We can measure decay particles over large angular coverage by installing a 24Mg target in the sensitive volume of MAIKo-TPC. We should use a high-intensity beam at about 1010cps to achieve sufficient statistics in the experiment. When such a high-intensity beam is introduced to the 24Mg in a conventional TPC, however, there occur serious problems such as distortion of the electric field or electric discharges due to many electrons and ions induced by the high-rate beam. In order to avoid these problems, we have developed a mask to make an insensitive region along the beam trajectories. In the present talk, we will report an overview of the experiment to search for the αcondensed state in 24Mg and the result from the performance test of MAIKo-TPC using the high-intensity beam. |
Thursday, October 25, 2018 10:15AM - 10:30AM |
DH.00005: Cluster Structure and Three-Body Decay of 14C Lisa Carpenter, Clementine Santamaria, Wolfgang Mittig, Daniel Bazin, Saul Beceiro Novo, Jaspreet S Randhawa, Nathan Watwood, Tan Ahn, Yassid Ayyad, Frederick D Becchetti, James J Kolata Recent model calculations with most advanced methods for cluster states have shown the need of experimental data to probe the structure of light exotic nuclei, including those with α-clustering, such as 14C. The prototype Active Target Time Projection Chamber (pAT-TPC) allows us to investigate these types of structures. This type of detector allows access to the excitation function at all energies and angles with a single beam energy. The measurement was carried out by resonant alpha-scattering of a 10Be beam at 40 MeV delivered by the TwinSol facility at the University of Notre Dame. This type of experiment measures resonances in 14C that can be compared to the models using R-Matrix reaction theory. Additionally, using a Dalitz-type analysis, three-body decays can be analyzed to determine probabilities of "democratic" and "sequential" decay. Results will be presented focusing on new high-energy resonances and three-body decay analysis. |
Thursday, October 25, 2018 10:30AM - 10:45AM |
DH.00006: 22Mg(α,p)25Al measured with the ATTPC in ReA3 Saul Beceiro Beceiro-Novo, Yassid Ayyad, Wolfgang Mittig, Daniel Bazin The 22Mg(α,p)25Al reaction was mesured with a 5MeV/u 22Mg beam in order to measure the cross section over a wide centre-of-mass energy range to disentangle the existing discrepancies among the existing statistical calculations. The experiment was recently performed using the Active Target Time Projection Chamber (ATTPC) that overcomes the difficulties imposed by the solid targets when using low intensity beams. The ATTPC was filled with He gas with enough pressure to stop the incoming 22Mg with a two-fold purpose: maximize the efficiency of the detector close to 100% while measuring the whole excitation function within the region of interest for the 22Mg(α,p)25Al reaction. Experimental data for this direct measurement will play a key role in network calculations. Preliminary results will be presented |
Thursday, October 25, 2018 10:45AM - 11:00AM |
DH.00007: Performance evaluation of Dual Gain Multi-layer Thick GEM for CAT with high-intensity heavy-ion beams Chihiro Iwamoto A prototype of dual gain multi-layer thick GEM was produced to construct large volume active target CAT-M. The GEM consists of alternate layers of electrodes and insulators, and effectively works as three layers of GEMs. The total thickness is 1.2 mm. Distortion of electric field in the GEM is expected to be small even if the area of the GEM become large because of its rigidness. The electrodes are divided into three regions to control gain at each region independently. In order to reduce space charges in drift region due to feedback ions and current at the electrodes caused by high intensity heavy-ion beams, gain in a region along the beams should be operated lower. Performance of the GEM was evaluated at a synchrotron accelerator facility HIMAC (project number: 15H307) by employing an active target CAT-S filled with 0.4-atm H2 gas. A 132Xe beam with the intensity up to 1 M particles per pulse was impinged into CAT-S. Position and beam intensity dependence of effective gas gains and energy resolutions have been obtained via track reconstruction. |
Thursday, October 25, 2018 11:00AM - 11:15AM |
DH.00008: Texas Active Target (TexAT) - design, commissioning and first results. Grigory Rogachev, Evgeniy Koshchiy, Emanuel Pollacco, Ethan E Uberseder, Joshua Hooker, Sunghoon Ahn, Sriteja Upadhyayula Texas Active Target is a general purpose time projection chamber (TPC) embedded into shells of Si and CsI(Tl) detector arrays. It is designed for nuclear reactions studies with rare isotope beams. The main focus of physics program with TexAT is structure of exotic nuclei and nuclear astrophysics. TexAT employs Micro-MEsh GAseous Structure ("Micromegas") detector and Generic Electronic System for TPCs (GET). We will discuss design, performance, and results of the first commissioning experiments performed with radioactive beams produced by Momentum Achromat Recoil Separator (MARS) at the Texas A&M University Cyclotron Institute. |
Thursday, October 25, 2018 11:15AM - 11:30AM |
DH.00009: Machine Learning Methods for Track Classification in the AT-TPC Michelle Perry Kuchera, Jack Z Taylor, Raghu Ramanujan, Daniel Bazin, Joshua W Bradt Track classification methods were evaluated for reaction products in the Active-Target Time Projection Chamber (AT-TPC) at the National Superconducting Cyclotron Laboratory (NSCL). Single-class, binary, and multi-class event classification methods were benchmarked on data produced by the $^{46}$Ar(p,p) experiment which ran at the NSCL in September of 2015. The experiment ran with a 1.68 T magnetic field parallel to the beam axis, producing spiral tracks. Results from logistic regression, feed-forward neural networks, convolutional neural networks, and support vector machines will be presented. We will compare classification of experimental data with simulated training data versus experimental training data. Recommendations for choosing appropriate event classification methods in future AT-TPC experiments will be made. |
Thursday, October 25, 2018 11:30AM - 11:45AM |
DH.00010: Particle Identification using ACTAR TPC Demonstrator. Kaito Hagiwara The active target and time projection chamber (ACTAR-TPC) is a collaborative European project whose goal is to develop a next-generation gas-filled detection system. It uses a gas volume that serves both as a sensitive detector and as the nuclear reaction target itself. The ionization products are drifted towards an amplification and collection plane consisting of 16k 2x2 mm2 pads. The ACTAR-TPC demonstrator, which is 1/8 scale of the final design, was built and an experiment was carried out to study the 6Li+α and 12C+12C reactions using a He+CO2 or C4H10 gas target. |
Thursday, October 25, 2018 11:45AM - 12:00PM |
DH.00011: A Dual Phase TPC/Thick-gem Based Target to Study Unbound Nuclei Angel C. Christopher, Paul L Gueye, Thomas Baumann, Marco Cortesi, Malinga Rathnayake The Facility for Rare Isotope Beams (FRIB) is currently being constructed on the campus of Michigan State University. When completed, FRIB will become an unprecedented low energy nuclear physics facility in the world to study neutron rich nuclei with heavy ion beams. The MoNA Collaboration, which consists of 11 institutions, has been involved at the National Superconducting Cyclotron Laboratory for almost two decades. Hampton University joined the collaboration in 2013 and led the development of a Si-Be segmented target that was used to measure the lifetime of 26O and neutron unbound states in the island of inversion using the invariant mass technique. This target provided for the first time detail information about the incident beam position and energy, before and exiting the Be targets to within 10%. A proposal to construct a dual-phase based time-projection chamber is being investigated by the MoNA Collaboration since it would increase the position and energy resolutions, and allow missing mass reconstruction by detecting the recoil fragments. Results from a realistic Geant4 Monte Carlo that include expected performances of this proposed target will be presented. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700