NeuLAND - FAIR

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events events 3000 2000 1000 8000 6000 4000 2000 1 n 2 n 3 n 4 n 0 0 10 20 30 E* (MeV) 0 0 10 20 30 E* (MeV) events events 8000 6000 4000 2000 4000 2000 0 0 10 20 30 E* (MeV) 0 0 10 20 30 E* (MeV) Figure 4.20.: The input excitation energy distribution (dashed lines) and its reconstruction from the R 3 BRoot simulation (solid lines) is displayed, similar as in figure 4.19, but for the individual neutron decay channels. The upper left panel shows the one neutron case (red), the upper right panel the two neutron decay channel (cyan), the lower left panel the three neutron case (blue) and the lower right panel the four neutron decay channel (magenta). In contrast to the display in the previous figure, here the efficiency correction of the individual neutron channels is not applied for the reconstructed data. 62
events 2000 1500 1000 500 σ = 15 keV 0 0 0.2 0.4 Erel (MeV) Figure 4.21.: Relative energy spectrum for one neutron events at 600 MeV, simulated with a relative energy of 100 keV with respect to a medium-heavy nucleus and the NeuLAND detector at 35 m distance to the target. Multi-Neutron Configurations The correct multi-neutron recognition is an essential improvement of NeuLAND over the nowadays existing fast-neutron detectors. We detail here the response of NeuLAND to a prime challenge of detector physics: the detection of 4 fast neutrons with a narrow distribution in space and time. Four correlated neutrons may occur in the breakup of four-neutron halo nuclei like 8 He and 14 Be. Their understanding is essential for the study of, e.g. the 7 H system, as discussed in section 2.3. Excellent 4-neutron detection efficiencies are expected, based on simulations, see section 4.5.3, i.e. table 4.5. In order to mimic the tetra-neutron case, we investigate the detection capabilities of NeuLAND for a scenario, where 4 neutrons plus the projectile fragment share a relative energy of only 100 keV. NeuLAND is situated at the maximum distance of 35 m and we select 600 AMeV as a typical beam energy. Figure 4.22 displays the reconstructed relative energy spectrum for this scenario. We observe a distribution, which has a gaussian-like peak plus an exponential tail to higher relative energies. Fitting the gaussian part, as displayed in figure 4.22, results in σE = 42 keV. We find 58% of all entries within a 2σ-interval. For an estimate on the fraction of correlated 4-neutron events, which will be resolved by NeuLAND, we must take the total 4-neutron-recognition probability of about 60% into account, see table 4.5. Therefore, about one third of the impinging 4-neutron events can be resolved with good resolution using the present neutron tracking algorithm. For the events in the exponential tail, see figure 4.22, the first interactions have not been fully resolved for all four neutrons, thus leading to a false reconstruction of the relative energy. This effect is observed similarly in the case of multi-neutron contributions to the GDR, (we refer to the first example of 63
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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
Page 12 and 13: Apart from the excellent energy res
Page 14 and 15: 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: events 15000 10000 5000 input outpu
Page 65 and 66: 5. Technical Specifications and Des
Page 67 and 68: construction, or for subsequent rep
Page 69 and 70: positioning of 50 submodules mounti
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 %
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B.7. MRPC Solution using Glass as C
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114
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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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NeuLAND - FAIR

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