NeuLAND - FAIR

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Figure 5.1.: Technical drawing of NeuLAND submodules together with its light guides. In order to exclude possible losses at the optical borders between scintillator and light guide, the scintillator bar and its light guides are produced in one piece from the RP- 408 material, as detailed in in the upper part of figure 5.1. This also simplifies the mounting structure of the modules, because no dedicated holding device is needed for the light guides. Another advantage of this one-piece solution is, that we can omit optical coupling materials, which otherwise might lead to possible aging issues. 5.2.3. Light Readout At the stage of writing of this Technical Design Report we propose a conventional photomultiplier readout for the photons produced in the scintillator bars. However, as an investment in the future we closely follow the fast development of semiconductor devices for fast-timing readout, in particular so- called Silicon-Photomultipliers (SiPM). These devices seem to fulfill the time resolution needs of NeuLAND. However, the currently available SiPM sizes of up to 10×10 mm 2 are insufficient to fulfill the needs for Neu- LAND, and their dark count rate is too high. Depending on the progress within this field, a SiPM- based readout remains an option, either for the later phases of NeuLAND 66
construction, or for subsequent replacements of broken photomultipliers in a possible refurbishing of NeuLAND. In order to stay abreast of developments and to drive progress in the directions needed for NeuLAND, we participate in the Nuclear Physics Network (NUPNET) ERA-Net, in the NEDENSAA (NEutron DEtector developments for Nuclear Structure, Astrophysics and Applications) project that runs from 2011-2014. NeuLAND is included in the NE- DENSAA working package 4 on photon readout, concentrating on large area, and low dark rate SiPM’s. This NeuLAND-oriented NUPNET work has strong synergies with the NUPNET engagement of the CALIFA working group in the FATIMA (Advanced Fast Timing Arrays with novel scintillators and photosensors) NUPNET. The work of the CALIFA group within FATIMA also aims to improve the readout of SiPMs. Presently, a read-out of NeuLAND with conventional photomultiplier tubes is not only viable but also state of the art. However, we are actively participating in the development of a promising, alternative that might become a cost-saving alternative in the future. We select the R8619-Assembly photomultiplier from Hamamatsu [Ham-11], or equivalent, for the readout of the NeuLAND submodules. This device with a diameter of 1 inch and a peak sensitivity of 420 nm fits well to the RP408 scintillator bars, via the light-guide coupling discussed above. With a gain of 2 × 10 6 and an anode rise time of 2.6 ns it offers a cost-effective solution adapted to the needs of NeuLAND. First tests of a final shape NeuLAND module with these photomultipliers in electron beams (section 3.3) indicate a time resolution of σt = 125–135 ps, which is sufficient for the resolutions aimed for with NeuLAND. 5.3. Full Detector Assembly 5.3.1. Grouping of Submodules — Double Planes The scintillator bars will be grouped in double planes, each plane consisting of 50 submodules to build up a face-size of 250 × 250 cm 2 . The orientation of the bars of the second plane is rotated by 90 ◦ with respect to the first one. Two planes share a holding structure, displayed in figure 5.2, the scintillator bars are locked into position via the conical drill-holes, which support the light-guide part of the bars. The frame plates are made from aluminium, about 265 cm long, 10 cm wide and 3 cm thick each. Figure 5.3 details the attachment of read-out devices to the double planes. The photomultipliers are mounted to the outside of the holding frame with a Mu-metal tube, a Kapton foil inside serves for electrical insulation. A bayonet cap allows for an easy access to the photomultiplier and attached voltage divider. The light-tightness is assured by O-rings at both connection ends of the Mu-metal tube. The photomultiplier window is pressed to the light-guide end of the scintillator bar through a spring included in the bayonet cap. In figure 5.4 the sequence for building up the scintillator bars in 67
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FAIR/NUSTAR/R 3 B/TDR NeuLAND Techn
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Germany EMMI and FIAS: Enrico Fiori
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INR Moscow: Alexander Botvina Russi
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Contents Executive Summary 11 1. In
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B.7. MRPC Solution using Glass as C
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Apart from the excellent energy res
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processes in the universe, such as
Page 16 and 17: decaying into 24 O plus 4 neutrons
Page 19 and 20: 2. Physics Scenarios: Requirements
Page 21 and 22: e studied at R 3 B at FAIR include
Page 23 and 24: all theoretical calculations predic
Page 25 and 26: at the surface of the nucleus. The
Page 27 and 28: the evolution of fission channels (
Page 29 and 30: 3. Summary of NeuLAND Prototype Res
Page 31 and 32: counts 70 60 50 40 30 20 10 0 15 15
Page 33 and 34: Figure 3.4.: Shown is the time reso
Page 35 and 36: 4. Monte Carlo Simulations Within t
Page 37 and 38: normalized counts normalized counts
Page 39 and 40: GEANT3 interface. Here, we compare
Page 41 and 42: Counts 1000 900 800 700 600 500 400
Page 43 and 44: counts 5 10 4 10 3 10 2 10 10 LAND
Page 45 and 46: incident neutron fully active detec
Page 47 and 48: investigated. Three values for the
Page 49 and 50: spectrum, absorption length, refrac
Page 51 and 52: Counts 600 500 400 300 200 100 with
Page 53 and 54: Since, as discussed above, several
Page 55 and 56: events 800 600 400 200 0 0 200 400
Page 57 and 58: clusters N 100 50 0 0 500 1000 1500
Page 59 and 60: In the following section we discuss
Page 61 and 62: events 15000 10000 5000 input outpu
Page 63 and 64: events 2000 1500 1000 500 σ = 15 k
Page 65: 5. Technical Specifications and Des
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Page 71 and 72: Figure 5.6.: Detector frame with fi
Page 73 and 74: 5.4. Peripheral Systems 5.4.1. Read
Page 75 and 76: Figure 5.12.: The photo shows the T
Page 77: 6. Radiation Environment and Safety
Page 81 and 82: 8. Calibration 8.1. Calibration wit
Page 83 and 84: Figure 8.3.: ToF distribution in 10
Page 85: Figure 8.4.: Event display for seve
Page 89 and 90: 10. Installation procedure, its Tim
Page 91: 11. Cost and Funding 11.1. Cost Est
Page 94 and 95: The timeline for milestone 1 includ
Page 96 and 97: 96 2. Sample Tests Random samples o
Page 98 and 99: PNPI St. Petersburg: G.D. Alkhazov,
Page 100 and 101: HV 1.$ mm 2$ mm 0+$1-2)-2'.%/ 5%4'.
Page 102 and 103: Beamline Be exit window P 6 P 3 P 4
Page 104 and 105: B.3. Design Issues Addressed with 4
Page 106 and 107: Time [ns] Counts 41 40 39 2200 2000
Page 108 and 109: Efficiency 100 80 60 40 20 0 7.5 8
Page 110 and 111: 200 AMeV, Erel = 100 keV emitted %
Page 112 and 113: B.7. MRPC Solution using Glass as C
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[Bot-04] S. Botvina andI.N. Mishust
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[Lip-03] C. Lippmann, PhD Thesis, U
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