The past 5 months when I was in SSL @ UCB…

Jeng-Lun Chiu (Alan)Department of Physics, NTHU /

SSL, UCB2006/12/19

Outline

• Introduction to NCT

• Data & simulation formats

• Charge sharing & Energy Loss

• Mgeant & MEGAlib

• Image Reconstruction

• PIXON algorithm

• Future Work

NCTNuclear Compton Telescope• Sources: Nuclear line emission & polarization • Energy-band: Soft gamma-ray (0.2-10 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 th

e 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 0.511-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 2005 @ NTHU )

( M. E. Bandstra, 2006 IEEE )

( E, x, y, z, t )

Simulation

Data

.out [9]

.txt [7]

.bin

.str

.dat [15]

.gif

mgeant sharexi

nt

wrfile

reconstruct

IDL

prbin

(bin)

(bin)

(..etc)

Procedure for analysis

“Readme.txt” by J. D. Bowen, Jul 14, 2006

Event number

Energy

X DSP

Multi. # /

order

Y Z veto

Simulation(/data) formats

Event number

Event clock

E (DC)

E (AC)

X-strip

Y-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 sharexi

nt

wrfile

reconstruct

IDL

prbin

(bin)

(bin)

(..etc)

Procedure for analysis

“Readme.txt” by J. D. Bowen, Jul 14, 2006

Imakefile

input.dat( simulation param

eters )

mgeantexcuta

ble

usrinp.F

gmake

SCAN2

INTER BATCH

output

others...

version, format,beam, spec, ( hadronic inter. )

Kine, Trig, Beam, Spec, Threshold, output filename, etc..

setup.geo( creation of geome

tries )

media.med

( define material types )material.mat

( define materials )

Information on the header of output file ..etc

GEANTGEANT3 3

mgeantmgeant

Interface for “Geant3” simulation

http://astrophysics.gsfc.nasa.gov/astroparticles/programs/mgeant/

MEGAlib picture

MEGAlib: completely object-oriented (written in “C++ & ROOT”)

Geomega: providing geometry & detector description module

Compton, Pair, etc.. Unsequenced hits

MGGPODConvert-

MGGPOD RevanEvent

Reconstruction

MimrecHigh-level

data analysis & Image

reconstruction

tra

Responsegenerator

GMegaGeant3

simulation

CosimaGeant4

simulation

sim

Detector(real data)

SivanSimulation verification

MEGAlyzeData acquisition

& calibration

Geant3

Geant4 fits

fits

fits

evta

bin

A. C. Zoglauer, 2006

GeoMega – Geometry for Mega

Revan – Real event analyzer

Mimrec – Mega image reconstruction

( http://www.mpe.mpg.de/MEGA/megalib.html )

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 order

s of magnitude (3) Ensure robust rejection of spurious sources

PIXONPIXON

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. 226-229 (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. 54-63 (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).

• Andreas Zoglauer, "First Light for the Next Generation of Compton and Pair Telescopes", TU Munich, 12/2005

• Talks in CIS workshop @ NTHU, Nov. 15-17, 2005• Talks in NCT workshop @ NTHU, Sep. 11-12, 2006

• http://universe.gsfc.nasa.gov/astroparticles/programs/mgeant/ ( mgeant ) • http://www.mpe.mpg.de/MEGA/megalib.html ( MEGAlib )

• Piña R. K. & Puetter R. C., 1993, PASP, 105, 630 • R. C. Puetter, Ann. N.Y Acad. Sci., 808, pp. 160-183 (1997). • http://casswww.ucsd.edu/personal/puetter/pixonpage.html (The Pixon PAGE in UCSD)

• http://www.pixon.com/brochure.html (The PIXON method @ www.pixon.com)

~ Thank you ~