Tracking algorithms for the active target MAYA

📝 Abstract

The MAYA detector is a Time-Charge Projection Chamber based on the concept of active target. These type of devices use a part of the detection system, the filling gas in this case, in the role of reaction target. The MAYA detector performs three-dimensional tracking, in order to determine physical observables of the reactions occurring inside the detector. The reconstruction algorithms of the tracking use the information from a two-dimensional projection on the segmented cathode, and, in general, they need to be adapted for the different experimental settings of the detector. This work presents some of the most relevant solutions developed for the MAYA detector.

💡 Analysis

The MAYA detector is a Time-Charge Projection Chamber based on the concept of active target. These type of devices use a part of the detection system, the filling gas in this case, in the role of reaction target. The MAYA detector performs three-dimensional tracking, in order to determine physical observables of the reactions occurring inside the detector. The reconstruction algorithms of the tracking use the information from a two-dimensional projection on the segmented cathode, and, in general, they need to be adapted for the different experimental settings of the detector. This work presents some of the most relevant solutions developed for the MAYA detector.

📄 Content

arXiv:1012.3560v2 [nucl-ex] 19 Jan 2011 Tracking algorithms for the active target MAYA T. Rogera,b,∗, M. Caama˜noc, C.E. Demonchyd, W. Mittige, H. Savajolsa, I. Tanihataf aGANIL, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 05, France bInstituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium cUniversidade de Santiago de Compostela, E-15786 Santiago,, Spain dCENBG-Universit Bordeaux 1-UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex, France eNSCL, MSU, East Lansing, Michigan 48824, USA fRCNP, Osaka University, Mihogaoka, Ibaraki, Osaka 567 0047, Japan Abstract The MAYA detector is a Time-Charge Projection Chamber based on the concept of active target. These type of devices use a part of the detection system, the filling gas in this case, in the role of reaction target. The MAYA detector performs three-dimensional tracking, in order to determine physical observables of the reactions occurring inside the detector. The reconstruction algorithms of the tracking use the information from a two-dimensional projection on the segmented cathode, and, in general, they need to be adapted for the different experimental settings of the detector. This work presents some of the most relevant solutions developed for the MAYA detector. Keywords: Active target, Gaseous detector, Trajectory reconstruction, Tracking algorithm, Simulation PACS: 29.85.Fj, 29.40.Gx, 29.40.Cs

1. Introduction Nowadays, the development of new radioactive beams allows nuclear physics to explore more exotic regions of the nuclear chart, revealing more new prop- ∗Corresponding author Email address: thomas.roger@fys.kuleuven.be (T. Roger) Preprint submitted to Nuclear Instruments and Methods A October 29, 2018 erties as they become experimentally available. The access to these regions usually involve exotic with low intensity and reactions with small cross-sections that force to improve detection and analysis techniques. To overcome these dif- ficulties, experimental setups focus on different solutions, such as high efficiency and signal-to-noise discrimination, and the use of thick targets. Active target detectors, i.e, detection devices that use part of their systems as reaction tar- get, proved to match these needs: since the detection is done inside the target, detection efficiency and effective target thickness are increased without losing resolution due to reaction point indetermination. The concept of active target, developed more than fifty years ago in high- energy physics uses, is being progressively adapted for its application in nuclear physics. The archetype of active targets in the domain of secondary beams is the detector IKAR [1], used at GSI (Germany) to study elastic scattering of exotic beams at relativistic energies. Another example is the MSTPC detector [2] designed at RIKEN (Japan) to study fusion and astrophysical nuclear reactions in low-energy regions. Presently, new designs are mostly based on gas-filled devices where the gas constitutes both the target and the detection medium. Among these, MAYA [3, 4], developed and built at GANIL, is designed to explore very low energy domains not accessible with the use of solid or liquid targets. The MAYA detector applies the concept of Charge and Time Projection to perform a full three-dimensional reconstruction of the detected reaction with the charge collected in a segmented cathode and its associated drift time. Most of the active targets in development use a similar configuration, with the tracking performed on a segmented layer. Therefore, some of the problems and solutions that appear in the reconstruction process are common to these detectors. In the case of MAYA, the tracking process needs to be adapted to the experimental configurations used to study different reactions, producing a collection of reconstruction protocols to extract the relevant observables. Among these, the angle, reaction vertex, and stopping points need specific formulas to be determined. Here, the most significant of these algorithms are reviewed. 2 isobutane 25 cm 20 cm 28 cm charged particles e_ Beam Frish grid Amplification wires Segmented cathode Ancillary detectors Figure 1: (Color online) The picture shows a schematic rendition of the MAYA active-target. A beam projectile enters the detector volume where it reacts with a nucleus in the gas. The particles involved in the reaction may produce enough ionization to induce a pattern in the segmented cathode, after traversing a Frisch grid and a plane of amplification wires. A set of ancillary detectors is used in the exit side of the detector.
2. The MAYA Detector Figure 1 shows a typical MAYA setup. Two main zones can be identified within the detector: an active volume of 28×26×20 cm3 where the reaction takes place, and the amplification area where detection and readout occur. The amplification zone consists of a Frisch grid, an anode wire plane below, and a segmented cathode in the lower part. The cathode is

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