Modular Neutron Array: Difference between revisions

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The '''Modular Neutron Array (MoNA)''' is a large-area, high efficiency [[neutron detector]] that is used in basic research of rare isotopes at [[Michigan State University]]'s [[National Superconducting Cyclotron Laboratory]] (NSCL), a nuclear physics facility. It is specifically designed for detecting [[neutrons]] stemming from breakup reactions of fast fragmentation beams.

== The MoNA Detector Array ==

In its original configuration, MoNA consisted of 9 vertical layers of 16 detectors each stacked in compact form, having an active area of 2.0 m wide by 1.6 m tall. In its current arrangement (depicted in the image to the right), it is stacked in four separate sections of 2, 2, 2, and 3 layers each, respectively, separated by spaces ranging from 0.5 to 0.8 meters. It measures both the position and time of neutron events with multiple-hit capability. The energy of a neutron is based on a time-of-flight measurement. This information together with the detected position of the neutron is used to construct the momentum vector of the neutrons.<ref>B. Luther et al., Nucl. Instr. And Methods A505, 33 (2003)</ref><ref>T. Baumann et al., Nucl. Instr. And Methods A543, 517 (2005)</ref>

The Modular Neutron Array consists of 144 individual detector modules. Each module is based on a plastic [[scintillator]] measuring 10 cm by 10 cm by 200 cm. This scintillator bar is fitted with light guides on each end that direct the light into one [[photo-multiplier tube]] on each end. Each detector module is wrapped in a light-tight material, allowing the detector array to be arranged in different configurations.

In its original configuration, MoNA consisted of 9 vertical layers of 16 detectors each stacked in compact formclosely, having an active area of 2.0 m wide by 1.6 m tall. In its current arrangement (depicted in the image to the right), it is stacked in four separate sections of 2, 2, 2, and 3 layers each, respectively, separated by spaces ranging from 0.5 to 0.8 meters. It measures both the position and time of neutron events with multiple-hit capability. The energy of a neutron is based on a time-of-flight measurement. This information together with the detected position of the neutron is used to construct the momentum vector of the neutrons.<ref>B. Luther et al., Nucl. Instr. And Methods A505, 33 (2003)</ref><ref>T. Baumann et al., Nucl. Instr. And Methods A543, 517 (2005)</ref>

The detection efficiency of MoNA is maximized for the high-beam velocities that are available at the NSCL's Coupled Cyclotron Facility (CCF). For neutrons ranging from 50 to 250 [[MeV]] in energy, it is designed to have an efficiency of up to 70% and expands the possible coincidence experiments with neutrons to measurements which were previously not feasible. The detector is used in combination with the Sweeper magnet<ref>V. Zelevinsky and A. Volya, AIP Conf. Proc. 819, 493 (2006)</ref><ref>S. Prestemon et al., IEEE Trans. Appl. Supercond. 11, 1721 (2001)</ref><ref>J. Toth et al., IEEE Trans. Appl. Supercond. 12, 341 (2002)</ref><ref>M. B. Bird et al., IEEE Trans. Appl. Supercond. 14, 564 (2004)</ref><ref>M. B. Bird et al., IEEE Trans. Appl. Supercond. 15, 1252 (2005)</ref> and its focal plane detectors for charged particles.<ref>N. Frank, Ph.D. Thesis, MSU (2006)</ref> In addition, MoNA’s modular design allows it to be transported between experimental vaults and thus to be used in combination with the Sweeper magnet installed at the S800 magnet spectrograph.<ref>D. Bazin et al., Nucl. Instr. and Meth. B 204, 629 (2003)</ref> Due to its high-energy detection efficiency, this detector will be well suited for experiments with fast fragmentation beams at the proposed ISF.