The Nu-SNS proposal - ORNL Physics Division - Oak Ridge ...

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Figure 3.3 Composition details at two points during stellar core collapse [35]. However, it is well known that the residual nuclear interaction (beyond the IPM) mixes the fp and gds shells, for example, making the closed 1g 9/2 shell a magic number in stable nuclei (N=50) rather than the closed fp shell (N=40). To examine the possibility that nuclear electron capture is not quenched at N=40, cross sections for charged-current electron and electronneutrino capture on many nuclei up to at least A=100 are needed to accurately simulate core deleptonization. Full shell model diagonalization calculations remain impossible in this regime due to the large number of available levels in the combined fp+gds system [27]. Langanke et al. [38] developed a “hybrid” scheme, employing Shell Model Monte Carlo (SMMC) calculations of the temperature-dependent occupation of the various single-particle orbitals to serve as input to Random Phase Approximation (RPA) calculations for allowed and forbidden transitions to calculate the capture rate. With this approach, Langanke et al. [39] ν-SNS Proposal 22 8/4/2005
(LMS) calculated electron capture rates for a sample of nuclei with A=66-112. As Figure 3.4 demonstrates, though the electron capture rates for individual heavy nuclei are smaller than that on protons, they are large enough that capture on the much more abundant heavy nuclei dominates the capture on protons throughout core collapse. Figure 3.4 Comparison between the electron capture rate on heavy nuclei to that on protons versus the electron chemical potential over the range found in a collapsing stellar core [38]. The upper panel shows the rates for individual species, the lower panel folds in the relative abundance of the protons and heavy nuclei. Hix et al. [40] used these rates, along with the shell model diagonalization rates of Langanke & Martinez-Pinedo [27] (LMP) for lighter nuclei, to develop a greatly improved treatment of nuclear electron capture. To calculate the needed abundances of the heavy nuclei, a Saha-like Nuclear Statistical Equilibrium expression was used, including Coulomb corrections to the nuclear binding energy [41,42], but neglecting the effects of degenerate nucleons [43]. Comparison between the long standard Bruenn prescription [8] (shown below in Equation 1) and the improved treatment of nuclear electron capture used by Hix et al., which we will term the LMSH prescription, reveals two competing effects. In lower density regions, where the average nucleus is well below N=40 and the cutoff of electron capture on heavy nuclei due to filling the neutron 1f 5/2 orbital, the Bruenn parameterization results in more electron capture than the ν-SNS Proposal 23 8/4/2005
Page 1: ν ν
Page 5 and 6: TABLE OF CONTENTS LIST OF FIGURES .
Page 7 and 8: APPENDIX 1 ν-SNS INSTRUMENT DEVELO
Page 9 and 10: LIST OF FIGURES Figure Page 2.1 Dia
Page 11 and 12: 4.44 Block diagram of the ν-SNS fr
Page 13 and 14: LIST OF TABLES Table Page 1.1 Insti
Page 15 and 16: ACRONYM LIST ADC - Analog to Digita
Page 17 and 18: 1 EXECUTIVE SUMMARY Measurements du
Page 19 and 20: Our present cost estimate for the s
Page 21 and 22: 2 PROJECT OVERVIEW 2.1 Scientific M
Page 23 and 24: the detailed structure of the induc
Page 25 and 26: Figure 2.3 Time and energy distribu
Page 27 and 28: Proton Beamline ν-SNS Beamline 18
Page 29 and 30: detectors. Simultaneous operation a
Page 31 and 32: 3500 3000 2500 Escalated TPC (in as
Page 33 and 34: 3 SCIENTIFIC MOTIVATION There are m
Page 35 and 36: The neutrino energy deposition behi
Page 37: Figure 3.2 Energy scales and compos
Page 41 and 42: Figure 3.5 Comparison of the core v
Page 43 and 44: composition and spatial distributio
Page 45 and 46: supernova is initiated [62]. Other
Page 47 and 48: In addition, the appearance of back
Page 49 and 50: differential cross sections can pro
Page 51 and 52: Another example of the impact that
Page 53 and 54: sensitivity achieved by ν−SNS fo
Page 55 and 56: References for Section 3: 1. “Con
Page 57 and 58: 60. W.C. Haxton, Neutrinos In Physi
Page 59 and 60: 4 PROJECT DESCRIPTION The Spallatio
Page 61 and 62: 4.1.1 Neutrons Escaping from the Sp
Page 63 and 64: Flux (in n/cm 2 /s) Figure 4.3 Back
Page 65 and 66: Concrete plug High-density concrete
Page 67 and 68: Vertical Distance from Beam (cm) Ho
Page 69 and 70: 4.1.5 Cosmic Ray Backgrounds The co
Page 71 and 72: • All backgrounds by utilizing pa
Page 73 and 74: eamline will be removable, with the
Page 75 and 76: Table 4.1 Cost breakdown for the sh
Page 77 and 78: 4.3.3 Simulated Performance In orde
Page 79 and 80: (0.005%). Using current neutron flu
Page 81 and 82: Figure 4.15 Conceptual design of on
Page 83 and 84: Table 4.2 Cost breakdown for the co
Page 85 and 86: 4.4 Segmented Detector 4.4.1 Requir
Page 87 and 88: Counts (arbitrarily normalized ) Fi
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As expected, thinner targets allow
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Counts (arbitrary normalization) Ne
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Counts (normalized for one year ful
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Counts (normalized for one year ful
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In conclusion, Monte Carlo studies
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Sense wires are held at high voltag
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Table 4.5 Cost breakdown for the se
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4.5 Homogeneous Detector 4.5.1 Requ
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A candidate for the PMTs to be used
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from control samples recorded durin
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The visible light signal recorded i
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Figure 4.43 Relative PMT light coll
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Table 4.6 Cost breakdown for the ho
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4.6 Common Data Acquisition System
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Table 4.7 Cost breakdown for the co
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Section 4 References: 1. MCNPX Team
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5 COST AND SCHEDULE 5.1 Work Breakd
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Example: Machining Bunker Steel Pla
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Table 5.4 Proposed ν-SNS budget pr
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6 MANAGEMENT PLAN AND PROJECT CONTR
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We respond to these special charact
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6.5 Quality Assurance and Control T
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see Appendix 5 for details. The lar
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APPENDIX 1 ν-SNS INSTRUMENT DEVELO
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APPENDIX 2 CURRICULUM VITAE OF ν-S
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Professional Vitae Summary Fred E.
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JEFF C. BLACKMON Physics Division,
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Vince Cianciolo Physics Division, O
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Biographical Sketch YURI EFREMENKO
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Curriculum Vitae TONY A. GABRIEL Ex
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• Past Member, Organizing Committ
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Dr. rer. nat. Uwe Greife, Associate
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Physics Division Oak Ridge National
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Biographical Sketch Gail C. McLaugh
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ION STANCU Department of Physics an
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21. D.V. Ahluwalia, Y. Liu and I. S
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APPENDIX 3 SNS REVIEW RESULTS In Su
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ν-SNS Proposal A-29 8/4/2005
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poorly known neutrino-nucleus cross
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APPENDIX 4 SNS TARGET HALL FLOOR LO
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APPENDIX 5 ν-SNS R&D PROGRAM Detec
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Segmented Detector Mechanics The se
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