status report on light simulator claudia cecchi francesca marcucci monica pepe software meeting...
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Status report on Light Simulator
Claudia Cecchi Francesca Marcucci
Monica Pepe
Software meeting Udine
January 30-31 2003
Why the light simulator…
Fast simulation of the sky map seen by GLAST to be used starting point for statistical analysis.
Generation of a photon list, with photons distributed randomly,
according to PSF, AS and ED distributions (determination of
the true and measured energy, the incidence angle, the true and
the measured position and the arrival time of the photons)
The code (C++) is working under windows and under Linux
Next step: generation of a database with photon’s information available on the web.
Input: map of the galactic background (Egret or Galprop) Third Egret Catalogue with sources photon energy range (0.1 – 100 GeV) region of the sky (-90° - 90°, -180° - 180°) orbit or fix time
Simulation: extragalactic background
Output: FITS-images of sky-map view and sources
galactic background
sources
exposure
convolution
Bkg-differential flux C (P0) ( cm-2 t-1-1) = all contributions
map of the sky in small regions of 0.5° x 0.5° without detector effects convolution of our result with the SA, PSF and ED.
Convolution with PSF, SA and EDBackground and Sources
For Bkg:= 2.1I0 =C (P0) • =dl · db · cos(b)
In each pixel P0:
D(E) = 0-60° E(θ,E) · I0 •E –dθ
Generation of a photon list
N = E D(E)
Each randomly distributed in the map with:
random energy Etrue[Emin, Emax] according to D(E)
inclination angle θ distributed according to E(θ, Etrue)
Emeas obtained using the function ED(Etrue , Emeas )
angular distance, ρ, from origin point P0 (l0, b0) consistent with PSF( , Etrue )
final position of each photon is P1 (l1, b1) obtained considering that the total angular distance from P0 is
New w.r.t. the previous version
Calculation of Sun/Moon positions and angle with respect to SC
Mcllwain’s parameters calculation with GEOPAK
New Exposure improved SC latitude and longitude calculation
New PSF from S. Digel and J. Norris, depending on the incidence angle and on conversion point in the detector, front (2.5% X0 – 12 layers), back (25% X0 – 4 layers).
Faint sources, model from Stecker and Salomon ’96; flux (E> 100 MeV) between 10-10 and 10-7 photons cm-2 s-1.
Arrival photon’s time : the number of generated photons follows a Poissonian distribution
Spacecraft and orbit parameters
Output: two tables Photon parameters
FITS-images of sky-map view and sources
Photon Time
Arrival photon’s time : the number of generated photons follows a Poissonian distribution
Time interval from zero to T where T is the minimun interval of time with Nph different from zero
T divided into n steps t of 100 s (GLAST dead time)
For each step calculate the probability P that a photons is in t
if P < Rate t timephoton = n t
PSF comparison
OLD PSF (S. Ritz) is assumed to be a single gaussian, does not depend on the incidence angle and is averaged over converter thickness
NEW PSF (S.Digel & J.Norris) is the sum of two
gaussians, 1(95%) 2 (68%), depends on the incidence angle and on the conversion point (Front or Back)
Old PSF
New PSF
StartDate EndDate SCposX SCposY SCposZ LatRaZ LatDecZs s Km Km Km deg deg
30 60 6920 200 109 1,33 -29,460 90 6910 400 218 1,43 -28,690 120 6890 600 326 1,53 -27,7
LatRaX LatDecX RaZ DecZ SCmode Tlive ins SAAdeg deg deg deg s12,2 -35,9 0,11 0,9 1 27 012,5 -36,8 0,22 1,8 1 27 012,7 -37,7 0,33 2,7 1 27 0
SClon SClat SCalt SunRA SunDEC MoonRA MoonDECdeg deg km deg deg deg deg-108 0,91 550 4,9 -0,4 4,45 -0,41-100 1,81 550 4,9 -0,4 4,45 -0,41-107 2,72 550 4,9 -0,4 4,45 -0,41
Emeas Etrue ED(Etrue) Theta RAtrue DecTrue RAmeasGeV GeV GeV deg deg deg deg0,09 0,11 0,1 26 275 -27,7 2790,26 0,19 0,08 14 275 -27,7 2730,16 0,15 0,09 16,1 275 -27,7 274
DecMeasphoton time time DeadTimeZenith angleEarth Azimut angledeg s s s deg deg-28,6 54,4 90 0 62 75,1-26,6 112 150 0 65,6 77,8-29,9 117 150 0 65,6 77,8
SC x SC y SC z B LLat GeoMagLong Geomagkm km km gauss Earth radii deg deg
5630 -3570 -1890 3750 146 1,48 5,245880 -3230 -1710 3820 142 1,48 5,245880 -3230 -1710 3820 142 1,48 5,24
Bkg + sourcessources
Long (deg)
Lat
(deg)
Lat
(deg)
Long (deg)
3C279-60 sky + sources 0.1-30GeV Bg with PSF 827 orbits
Previous version
New version ANGLE- PSF total3C279-60 sky + sources 0.1-30GeV Bg with PSF (no Front-Back) 827 orbits
Bkg + sources sources
Bkg + sources sources
Long (deg)
Lat
(deg)
Lat
(deg)
Long (deg)
3C279-60 sky + sources 0.1-30GeV Bg with PSF 827 orbits
New version
0 20 40 60 0 20 40 50
Lat
(deg)
Lat
(deg)
3010
CONCLUSIONS and PERSPECTIVES
Last version is not running under Linux, problems with GEOPAK, under investigation
Simulation of 1 year of GLAST data tacking generation of a photon’s DB (under Linux)
First version of a note has been sent to S. Digel, new version with modifications ready for next week
Implementation of an algorithm to retrieve photon information from pixel index (Gino)
Implementation of the simulator in Gaudi as a standalone package (in collaboration with Toby)
Possibility of studying the PSF from Gleam to be used in the simulator (discussion)
255 sources from the Third Egret Catalogue
3EG J0010+7309 2.56 73.17 119.92 10.54 1.8464610E+00 4.8522080E+02 1.6500180E-103EG J0038-0949 9.74 -9.82 112.69 -72.44 2.7042760E+00 1.5626760E+02 5.3436390E-103EG J0118+0248 19.6 2.81 136.23 -59.36 2.6336160E+00 1.7153680E+02 2.3813020E-103EG J0130-1758 22.7 -17.97 169.71 -77.11 2.5050740E+00 1.9170150E+02 3.2784570E-103EG J0159-3603 29.84 -36.06 248.89 -73.04 2.8922490E+00 1.2666270E+02 8.0606110E-103EG J0204+1458 31.11 14.97 147.95 -44.32 2.2321450E+00 2.6488440E+02 1.3811020E-103EG J0210-5055 32.58 -50.93 276.1 -61.89 1.9899620E+00 2.8397580E+02 8.8435840E-103EG J0215+1123 34 11.38 153.75 -46.37 2.0280930E+00 6.0997420E+02 8.8540930E-123EG J0222+4253 35.7 42.9 140.22 -16.89 2.0100220E+00 4.1280090E+02 9.5417540E-113EG J0229+6151 37.32 61.86 134.2 1.15 2.2863630E+00 2.3071570E+02 5.4674250E-10
Source name AR DEC Long. Lat. Spectral index Standard energy Flux @st.energy
Elliptic orbit defined by the following parameters:
· a semi-major axis of the ellipse (distance of the orbit from the Earth 550 Km)· e eccentricity (is set to zero, because we assume a circular orbit)· P epoch (time of transit to the perigee)· T period ( 5739 s )· anomaly (the angle between the perigee and the point from where we start to calculate the orbit)· i inclination of the orbit with respect to the terrestrial equator (28.5°)· (t) the orientation of the semi-major axis of the ellipse· R rocking (35°). Simulated with a geometrical approach by steps of 30 ( 2°) assuming that within each step the parameters are constant. Output total exposure calculated as the sum over all the steps.
The orbit
Differential flux of photons from diffuse extra galactic background described (Skreekumer, 1997) as:
[1]
(photons · cm -2· s -1 · GeV -1· sr -2)
Total contribution of the extra galactic background obtained by the integration of (1) between Emin and Emax
taken into account only if |b| > 15°.
Diffuse extra galactic background
2.1-2.16- E · 0.451 · 10 · 7.3dE
dN
Galprop simulates the gamma ray background taking into account: neutral pion decay; bremsstrahlung; inverse Compton scattering.
Galprop produces FITS file containing 24 imagesin the energy range from 0.001 to 104 GeV
The gamma ray galactic background
EGRET map measured between 0.1 and 30 GeV
First approximation: sources point-like located at an infinite distance Intensity of photons:
(photons cm -2 s -1 GeV -1 )
Sources information: localization, and I0 from Third Egret Catalogue.
EIEI 0)(
Sources