Nab: Measurement Principles, Apparatus and Uncertainties Dinko Poˇ cani´ c (for the Nab Collaboration) University of Virginia Particle Physics with Slow Neutrons, ILL, Grenoble, 29–31 May 2008 D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 1 / 19
Outline Outline Experiment Basics Collaboration Motivation and Goals Nab measurement principles Proton TOF and e- ν correlation Spectrometer design Detection function Overview of uncertainties Event statistics, rates, running time Systematic uncertainties Summary D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 2 / 19
Basics Collaboration Nab Collaboration Arizona State University R. Alarcon, S. Balascuta, Los Alamos Nat’l. Lab. A. Klein, W.S. Wilburn, University of Manitoba M.T. Gericke, Univ. of New Hampshire J.R. Calarco, F.W. Hersman, A. Young, North Carolina State U. Oak Ridge Nat’l. Lab. J.D. Bowman, T.V. Cianciolo, S.I. Penttil¨ a, K.P. Rykaczewski, G.R. Young, Univ. of South Carolina V. Gudkov, G.L. Greene, R.K. Grzywacz, University of Tennessee University of Virginia L.P. Alonzi, S. Baeßler, M.A. Bychkov, E. Frleˇ z, A. Palladino, D. Poˇ cani´ c. Home page – http://nab.phys.virginia.edu D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 3 / 19
Basics Motivation and Goals Goals of the Experiment ◮ Measure the electron-neutrino parameter a in neutron decay ∆a ≃ 10 − 3 with accuracy of a − 0 . 1054 ± 0 . 0055 Byrne et al ’02 current results: − 0 . 1017 ± 0 . 0051 Stratowa et al ’78 − 0 . 091 ± 0 . 039 Grigorev et al ’68 ◮ Measure the Fierz interference term b in neutron decay ∆b ≃ 3 × 10 − 3 with accuracy of current results: none D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 4 / 19
Basics Motivation and Goals Goals of the Experiment ◮ Measure the electron-neutrino parameter a in neutron decay ∆a ≃ 10 − 3 with accuracy of a − 0 . 1054 ± 0 . 0055 Byrne et al ’02 current results: − 0 . 1017 ± 0 . 0051 Stratowa et al ’78 − 0 . 091 ± 0 . 039 Grigorev et al ’68 ◮ Measure the Fierz interference term b in neutron decay ∆b ≃ 3 × 10 − 3 with accuracy of current results: none D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 4 / 19
Basics Motivation and Goals Goals of the Experiment ◮ Measure the electron-neutrino parameter a in neutron decay ∆a ≃ 10 − 3 with accuracy of a − 0 . 1054 ± 0 . 0055 Byrne et al ’02 current results: − 0 . 1017 ± 0 . 0051 Stratowa et al ’78 − 0 . 091 ± 0 . 039 Grigorev et al ’68 ◮ Measure the Fierz interference term b in neutron decay ∆b ≃ 3 × 10 − 3 with accuracy of current results: none D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 4 / 19
Basics Motivation and Goals Goals of the Experiment ◮ Measure the electron-neutrino parameter a in neutron decay ∆a ≃ 10 − 3 with accuracy of a − 0 . 1054 ± 0 . 0055 Byrne et al ’02 current results: − 0 . 1017 ± 0 . 0051 Stratowa et al ’78 − 0 . 091 ± 0 . 039 Grigorev et al ’68 ◮ Measure the Fierz interference term b in neutron decay ∆b ≃ 3 × 10 − 3 with accuracy of current results: none D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 4 / 19
Basics Motivation and Goals Neutron Decay Parameters (SM) dw ≃ k e E e (E 0 − E e ) 2 dE e dΩ e dΩ ν � k e · � � � � � k e × � � � k ν + b m k e k ν k ν � × 1 + a + � � σ n � · A + B + D E e E ν E e E e E ν E e E ν with: A = − 2 | λ | 2 + Re( λ ) a = 1 − | λ | 2 1 + 3 | λ | 2 1 + 3 | λ | 2 B = 2 | λ | 2 − Re( λ ) Im( λ ) D = 2 1 + 3 | λ | 2 1 + 3 | λ | 2 λ = G A (with τ n ⇒ CKM V ud ) ( D � = 0 ⇔ T inv. violation) G V D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 5 / 19
Basics Motivation and Goals Neutron Decay Parameters (SM) dw ≃ k e E e (E 0 − E e ) 2 dE e dΩ e dΩ ν � k e · � � � � � k e × � � � k ν + b m k e k ν k ν � × 1 + a + � � σ n � · A + B + D E e E ν E e E e E ν E e E ν with: A = − 2 | λ | 2 + Re( λ ) a = 1 − | λ | 2 1 + 3 | λ | 2 1 + 3 | λ | 2 B = 2 | λ | 2 − Re( λ ) Im( λ ) D = 2 1 + 3 | λ | 2 1 + 3 | λ | 2 λ = G A (with τ n ⇒ CKM V ud ) ( D � = 0 ⇔ T inv. violation) G V D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 5 / 19
Basics Motivation and Goals Neutron Decay Parameters (SM) dw ≃ k e E e (E 0 − E e ) 2 dE e dΩ e dΩ ν � k e · � � � � � k e × � � � k ν + b m k e k ν k ν � × 1 + a + � � σ n � · A + B + D E e E ν E e E e E ν E e E ν with: A = − 2 | λ | 2 + Re( λ ) a = 1 − | λ | 2 1 + 3 | λ | 2 1 + 3 | λ | 2 B = 2 | λ | 2 − Re( λ ) Im( λ ) D = 2 1 + 3 | λ | 2 1 + 3 | λ | 2 λ = G A (with τ n ⇒ CKM V ud ) ( D � = 0 ⇔ T inv. violation) G V D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 5 / 19
Basics Motivation and Goals n-decay Correlation Parameters Beyond V ud ◮ Beta decay parameters constrain L-R symmetric, SUSY extensions to the SM. [ Reviews: Herczeg, Prog. Part. Nucl. Phys. 46 , 413 (2001), Ramsey-Musolf, Su, Phys. Rep. 456 , 1 (2008)] ◮ Fierz interference term, never measured for the neutron, offers a sensitive test of non-( V − A ) terms in the weak Lagrangian ( S , T ). ◮ Measurement of the electron-energy dependence of a and A can separately confirm CVC and absence of SCC. [ Gardner, Zhang, PRL 86 , 5666 (2001), Gardner, hep-ph/0312124] ◮ A general connections exists between non-SM (e.g., S , T ) terms in d → ue ¯ ν and limits on ν masses. [ Ito + Pr´ ezaeu, PRL 94 (2005)] D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 6 / 19
Basics Motivation and Goals n-decay Correlation Parameters Beyond V ud ◮ Beta decay parameters constrain L-R symmetric, SUSY extensions to the SM. [ Reviews: Herczeg, Prog. Part. Nucl. Phys. 46 , 413 (2001), Ramsey-Musolf, Su, Phys. Rep. 456 , 1 (2008)] ◮ Fierz interference term, never measured for the neutron, offers a sensitive test of non-( V − A ) terms in the weak Lagrangian ( S , T ). ◮ Measurement of the electron-energy dependence of a and A can separately confirm CVC and absence of SCC. [ Gardner, Zhang, PRL 86 , 5666 (2001), Gardner, hep-ph/0312124] ◮ A general connections exists between non-SM (e.g., S , T ) terms in d → ue ¯ ν and limits on ν masses. [ Ito + Pr´ ezaeu, PRL 94 (2005)] D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 6 / 19
Basics Motivation and Goals n-decay Correlation Parameters Beyond V ud ◮ Beta decay parameters constrain L-R symmetric, SUSY extensions to the SM. [ Reviews: Herczeg, Prog. Part. Nucl. Phys. 46 , 413 (2001), Ramsey-Musolf, Su, Phys. Rep. 456 , 1 (2008)] ◮ Fierz interference term, never measured for the neutron, offers a sensitive test of non-( V − A ) terms in the weak Lagrangian ( S , T ). ◮ Measurement of the electron-energy dependence of a and A can separately confirm CVC and absence of SCC. [ Gardner, Zhang, PRL 86 , 5666 (2001), Gardner, hep-ph/0312124] ◮ A general connections exists between non-SM (e.g., S , T ) terms in d → ue ¯ ν and limits on ν masses. [ Ito + Pr´ ezaeu, PRL 94 (2005)] D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 6 / 19
Basics Motivation and Goals n-decay Correlation Parameters Beyond V ud ◮ Beta decay parameters constrain L-R symmetric, SUSY extensions to the SM. [ Reviews: Herczeg, Prog. Part. Nucl. Phys. 46 , 413 (2001), Ramsey-Musolf, Su, Phys. Rep. 456 , 1 (2008)] ◮ Fierz interference term, never measured for the neutron, offers a sensitive test of non-( V − A ) terms in the weak Lagrangian ( S , T ). ◮ Measurement of the electron-energy dependence of a and A can separately confirm CVC and absence of SCC. [ Gardner, Zhang, PRL 86 , 5666 (2001), Gardner, hep-ph/0312124] ◮ A general connections exists between non-SM (e.g., S , T ) terms in d → ue ¯ ν and limits on ν masses. [ Ito + Pr´ ezaeu, PRL 94 (2005)] D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 6 / 19
Nab measurement principles Proton TOF and e- ν correlation Nab Measurement principles: Proton phase space p p2 (MeV 2 /c 2 ) proton phase space 1.4 cos θ e ν = 1 1.2 1 0.8 cos θ e ν = 0 0.6 0.4 0.2 cos θ e ν = -1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 E e (MeV) Note: For a given E e , cos θ e ν is a function of p 2 p only. D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 7 / 19
Nab measurement principles Proton TOF and e- ν correlation Measurement principles: Proton momentum response Yield (arb. units) 1 E e = 0.075 MeV 0.8 E e = 0.236 MeV E e = 0.450 MeV 0.6 E e = 0.700 MeV 0.4 0.2 Slope = β e · a 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 p p2 (MeV 2 /c 2 ) D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 8 / 19
Nab measurement principles Spectrometer design Measurement principles: Spectrometer sketch Neutron Segmented Beam Si�detector TOF�region Decay transition Volume region acceleration region Elements of spectrometer to be shared with other n decay experiments, e.g., abBA . D. Poˇ cani´ c (UVa) The Nab Experiment/NPP-ILL 08 31 May ’08 9 / 19
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