1 / 12

HKS Analysis Status

HKS Analysis Status. Lulin Yuan / Hampton University HKS Collaboration Meeting Jefferson Lab, May 16, 2008. Spectrometer System Calibration Strategy. Minimize Chisquare w.r.t reconstruction matrix M by an Nonlinear Least Square method

rowa
Download Presentation

HKS Analysis Status

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HKS Analysis Status Lulin Yuan / Hampton University HKS Collaboration Meeting Jefferson Lab, May 16, 2008

  2. Spectrometer System Calibration Strategy • Minimize Chisquare w.r.t reconstruction matrix M by an Nonlinear Least Square method • Kinematics calibration: important to determine correct binding energy, energy resolution • Iteration Iteration procedure for optical calibration Better signal to background ratio More accurate bound state mass Starting optics New optics Calculate missing mass Select L, S0and hypernuclear bound states events Minimize Chisquare w.r.t reconstruction matrix M

  3. p(e,e’K+)&0 used for kinematics and optics calibration  HKS-JLAB CH2 target ~ 70 hours  = 660 keV M = -9 keV M = -18 keV Preliminary Counts (0.3MeV/bin) 0 Events from C Accidentals

  4. Analysis Status • Optical reconstruction matrices and kinematics almost final • Have quick estimate of B12L ground state (GS) cross section • Finished analysis for simulated HKS data. Results of blind analysis is being compared with correct optics • Better Fitting for L and S0 peaks in CH2 spectrum result in shift in binding energy for hypernuclear spectrum • Need precise energy loss correction in CH2 target and other targets in order to determine binding energy correctly

  5. Blind Analysis • Involved B12L bound states in calibration • The expected position and relative weights of bound states are determined by scan to find the minimized c2: c2_wid at each stage of the calibration

  6. Blind Analysis Step by Step Result • initial matrix • involving L and S • involving B12L 2 peaks at Excitation Ex~0 and Ex~-11.5 • involving B12L "core excited" peak at Ex~9.0 • involving B12L " 2nd core excited" peak at Ex~5.0 B12L spectrum at each stage (Ex=0 at binding energy 11.37 MeV)

  7. Blind Analysis: Final Result • Final matrix: 6 states are identified from simulated C12 target data, their binding energy (MeV) and relative counts to "ground state "are 11.43 ('Ground state'): counts 491 23.70 and 23.04: combined counts relative to GS 0.83 20.35: 0.29 16.70: 0.39 13.63: 0.11 • The L and S position and counts from simulated CH2 target: L : -0.031 from PDG value, 2291 count S: 0.022, 418 count Ex : binding energy 11.37 MeV

  8. BetterFitting for L and S0 • Better fitting for L and S0 peaks to improve confidence level and binding energy precision. Three fitting methods: • G+P: Gaussian + Polynomial • AV: Gaussian + Avoigtian • ASAV: Gaussian + Asymmetric Avoigtian

  9. Calibration by L and S0 L Fit

  10. Average Cross section: B12L GS • Quick estimate of B12L GS cross section as the average of 5 C12 run periods *Correction factors, solid angle and VPF Based on Okayasu’s PhD Thesis

  11. Average Cross section: B12L GS • Averaged B12L GS cross section (0-13 degree average) ds/dWL = 103.1±5.7 (stats)(nbar/sr) HNSS (E89-009) (0-4.6 degree average): ds/dWL = 155.0±24 (stats)(nbar/sr) ds/dWL(nbar/sr) Average Cross section gK+ Scattering Angle(degree) C12 Run Period

More Related