Study of Light -Hypernuclei by Spectroscopy of Two Body Weak Decay Pions This previous PR12-10-001 is now proposed as a part of combined experiments that can run at same time to maximize physics outcome Fragmentation of Hypernuclei and Mesonic Decay inside Nucleus Free: p + - 2-B: AZ A(Z + 1) + - • Liguang Tang • Department of Physics, Hampton University • Jefferson National Laboratory (JLAB) JLabPAC40, June 18, 2013
Future Project: Super Hypernuclear Physics Experiment at JLab Enge () Unified collaboration from the previous Hall A and C collaborations HRS (e’) Septum Combine the features of previous Hall A and C experiments, create an optimized future program w/ the CEBAF CW beam HKS (K) HES () Septum HRS – HKS: (e, e’K+) experiments for mass spectroscopy HKS – Enge or HKS – HES: New decay -spectroscopy experiment
Decay Pion Spectroscopy to Study -Hypernuclei Direct Production e’ Example: K+ 12C e * Ground state doublet of 12B B and p 12B E.M. 12Bg.s. Hypernuclear States: s (or p) coupled to low lying core nucleus 2- ~150 keV 1- 0.0 - 12C Weak mesonictwo body decay
Decay Pion Spectroscopy for Light and Exotic -Hypernuclei Fragmentation Process Example: e’ K+ Access to variety of light hypernuclei, some of which cannot be produced or measured precisely by other means 12C e * Fragmentation (<10-16s) p s 12B* 4H 4Hg.s. Highly Excited Hypernuclear States: s coupled to High-Lying core nucleus, i.e. particle hole at s orbit - Weak mesonictwo body decay (~10-10s) 4He
Study of Light Hypernuclei by Pionic Decay at JlabIllustration on the Main Features Comparison of Spectroscopic and Background - Production SPECTROSCOPY Light Hypernuclei to Be Investigated e e p * - K+ p A1Z1 stop (b) Additions from 9Li and its continuum (Phase II: 9Be target) 6 3/2+ AZ 1/2+ Jp=? VS 1- A2Z2 7Li A(Z-1) A1(Z1+1) 8He 9Li 8Li 5 (Z-1) = Z1+Z2; A=A1+A2 6Li 1/2+ 7H 3B background 1-? 5/2+ 3/2+ 2- 4 BACKGROUND e Previously measured e Ex Ex Ex 0 0 0 1 1 1 * 3 Mirror pairs K+ Ex 0 2 - p(n) ,(-) N 2 AZ (A-1)Z’ 8Be 8B 9Li 8H 7He 6He 9B 8He 3H 6Li 10Be 10Li 10B 12B 9He 7Li 9Be 5H 4H 6H 8Li 7H 11Be 11B 1 A 2 6 7 11 12 8 1 5 3 4 9 10
Illustration of Decay Pion Spectroscopy Additions from 12B and its continuum (Phase III: 12C target) (c) 1- 12B 9Be 10Be 8Be 9B 11B 10Li 9He 11Be 8H Jp=? 10B 5/2+ 3B background 8B (b) Additions from 9Li and its continuum (Phase II: 9Be target) 3/2+ 1/2+ 1- 7Li 8He 9Li 8Li 6Li 1/2+ 7H 3B background 1-? 5/2+ 3/2+ 2- Ex Ex Ex (a) 0 0 0 1 1 1 2-B decay from 7He and its continuum (Phase I: 7Li target) Ex 0 2 1-? 0+ 1/2+ 3H 6He 1/2+ 6H 4H 7He 3B background 3/2+ 5H 5/2+ Ex PMax PMin Ex 2 0 0 2 90.0 100.0 110.0 120.0 130.0 140.0 - Momentum (MeV/c)
Physics Goal of Decay Pion Spectroscopy • Precise measurement of ground state B (20keV) for a series of light hypernuclei with high resolution (130keV), spin-parity determination of g.s., charge symmetry breaking (CSB) from mirror pairs • Neutron rich light hypernuclei (- coupling) and neutron drip line limit (6H and 8H) • Formation of quasi free continuum and fragmentation mechanism Provide precise input for theoretical description of -N interaction. Since B and excitation are the only sources of experimental information, study wide range of hypernuclei is needed.
Preliminary Results from MAMI-C KAOS – SPEC-C 2011 Run Partial 4H 2A beam KID affected by huge rate of e+ at 0 We are convinced at least on 4H observation 2012 Run Partial 20A beam • Added 10cm Pb curtain • Luminosity increased • KID was still a problem • K+ singles increased just a little
Advantages of Jlab Experiment • Higher production rate (~9 times) • Excellent PID for both K+ and - • Less background (accidental or real) • Full coverage of the interested - momentum range • Can take data together with the (e, e’K+) experiment
Summary • High intensity CW beam at JLAB and the characters of electro-production make possible for high precision hypernuclear programs, among which the decay pion program is unique. • The decay pion spectroscopy program is able to provide precise and fundamental information needed to understand the YN and Y-Nucleus interactions. • We are convinced from the MAMI-C test runs that the technique works.