The past 5 months when I was in UCB… Jeng-Lun Chiu (Alan) Department of Physics, NTHU / SSL, UCB 2006/12/19

Outline Introduction to NCT Data & simulation formats Charge sharing & Energy Loss Mgeant & MEGAlib Image Reconstruction PIXON algorithm Future Work

NCT Nuclear Compton Telescope Sources: Nuclear line emission & polarization Energy-band: Soft gamma-ray ( MeV) & hard X-ray (8-100 keV) Targets: GRB (monitor), solar flares, TGFs (Terrestrial Gamma-ray Flashes), Interest: 511-keV galactic emission line, emission and acceleration mechanisms in the magnetospheres of gamma-ray pulsars, sources of 26Al as being core-collapsed supernovae or Wolf-Rayet stars Scientific goal: (1) MeV gamma-ray all-sky survey, (2) hard X-ray all-sky survey, (3) Gamma-Ray Bursts (GRBs), (4) cosmic rays, (5) Active Galactic Nuclei (AGN), (6) supernovae and supernova remnants, (7) X-ray binaries, (8) Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), (9) gamma-ray pulsars, (10) galactic MeV lines, (11) solar flares, and (12) Terrestrial Gamma-ray Flashes (TGFs) Calibration Lines (keV): 59.5 (241Am); 81.0, 356 (133Ba); 122, 136 (57Co); 662 (137Cs); 1173, 1333 (60Co). Pre-flight in 2005 Present status

Nuclear Compton Telescope ( S. E. Boggs, CIS workshop NTHU ) ( M. E. Bandstra, 2006 IEEE ) ( E, x, y, z, t )

Simulation Data.out [9].txt [7].bin.str.dat [15].gif mgeant sharexint wrfile reconstructIDL prbin (bin) (..etc) Procedure for analysis “Readme.txt” by J. D. Bowen, Jul 14, 2006

Event number Energy X DSP Multi. # / order YZ veto Simulation(/data) formats

Event number Event clock E (DC)E (AC)X-stripY-strip Sharing flag - X Sharing flag - Y DSP Multi. # | order ……………………………

Energy loss & charge sharing (AC) by Zong-Kai Liu

Energy loss & charge sharing (DC) by Zong-Kai Liu

Energy loss & charge sharing W. Coburn, et al., 2002, SPIE

Simulation Data.out [9].txt [7].bin.str.dat [15].gif mgeant sharexint wrfile reconstructIDL prbin (bin) (..etc) Procedure for analysis “Readme.txt” by J. D. Bowen, Jul 14, 2006

Imakefile input.dat ( simulation parameters ) mgeant excutable usrinp.F gmake SCAN2INTERBATCH output others... version, format, beam, spec, ( hadronic inter. ) Kine, Trig, Beam, Spec, Threshold, output filename, etc.. setup.geo ( creation of geometries ) media.med ( define material types ) material.mat ( define materials ) Information on the header of output file..etc GEANT 3 mgeant Interface for “Geant3” simulation

MEGAlib picture MEGAlib: completely object-oriented (written in “C++ & ROOT”) Geomega: providing geometry & detector description module Compton, Pair, etc.. Unsequenced hits MGGPOD Convert- MGGPOD Revan Event Reconstruction Mimrec High-level data analysis & Image reconstruction tra Responsegenerator GMega Geant3 simulation Cosima Geant4 simulation sim Detector (real data) Sivan Simulation verification MEGAlyze Data acquisition & calibration Geant3 Geant4 fits evta bin A. C. Zoglauer, 2006 GeoMega – Geometry for Mega Revan – Real event analyzer Mimrec – Mega image reconstruction ( )

Image Reconstruction Instrumental and atmospheric limitations  blurring of the image But deblurring (deconvolution) techniques tend to amplify the noise ( D: data ; H: PSF ; I: image ; N: noise )

PIXON - Basic Concepts Information theory: the most efficient (minimal description) model of the signal also does the best job of separating it from noise  Pixon method demands minimum complexity, or Algorithmic Information Content (AIC)  It selects the smallest number of basis functions that still adequately fit the data. PIXON: (1). A picture element (2). A fundamental unit of information in the image The smallest groupings of signal warranted by the quality of the data, and they are fundamental and indivisible units of picture information. An image’s pixon represent the minimum set of degrees of freedom necessary to describe the image. (PP93) Innovation: Pixon-element (each basis function)  minimum parameterization

Solution: Pixon method provides a solution: (1) It assigns a priori probabilities to different signal models, so a function that zigzags through noisy data has low probability, while a smooth function has a high a priori probability. (2) In Bayesian fashion, it maximizes not the usual maximum likelihood of the data, given the model, but the product of that likelihood and the prior probability of the model. Benefit: (1) Increase the spatial resolution by factors of several (2) Increase the sensitivity to low contrast sources by orders of magnitude (3) Ensure robust rejection of spurious sources

PIXON

Quick PIXON

Summary Data formats and processing procedures Simulation – mgeant to geant3 MEGAlib package PIXON algorithm C++ for object-oriented programming LM-ML algorithm GSE codes… Starting…

Future Work Image reconstruction – PIXON Ground Support Equipment (with Mark) Pointing & Aspect (with Mark) Calibrations (all) Data archiving (with Andreas) Analysis Software (Andreas leads all)

Reference W. Coburn, S.E. Boggs, S. Amrose, R.P. Lin, M.T. Burks, M. Amman, P.N. Luke, N.W. Madden, and E.L. Hull. Results of charge sharing tests in a Ge-strip detector. In 2001 IEEE Nuclear Science Symposium Conference Record. IEEE, New York, NY, Vol. 1, pp (2002). W. Coburn, S. Amrose, S.E. Boggs, R.P. Lin, M.S. Amman, M.T. Burks, E.L. Hull, P.N. Luke, and N.W. Madden. 3D positioning germanium detectors for gamma-ray astronomy. In SPIE-Int. Soc. Opt. Eng. Proceedings of Spie - the International Society for Optical Engineering, Bellingham, WA, Vol. 4784, pp (2002). J.D. Bowen, M.E. Bandstra, S.E. Boggs, W. Coburn, C.B. Wunderer, R.P. Lin, M. Amman, P.N. Luke, M.T. Burks, W. Craig, N.W. Madden, D.M. Smith, P. von Ballmoos, P. Jean. Pre-flight calibration of the prototype Nuclear Compton Telescope. In SPIE-Int. Soc. Opt. Eng. Proceedings of Spie - the International Society for Optical Engineering, Bellingham, WA, Vol. 6266, pp. (2006).Pre-flight calibration of the prototype Nuclear Compton Telescope. Andreas Zoglauer, "First Light for the Next Generation of Compton and Pair Telescopes", TU Munich, 12/2005First Light for the Next Generation of Compton and Pair Telescopes Talks in CIS NTHU, Nov , 2005 Talks in NCT NTHU, Sep , ( mgeant ) ( MEGAlib ) Piña R. K. & Puetter R. C., 1993, PASP, 105, 630 R. C. Puetter, Ann. N.Y Acad. Sci., 808, pp (1997). (The Pixon PAGE in UCSD) (The PIXON

~ Thank you ~