Skobeltsyn Institute of Nuclear Physics, Moscow State University. All-Sky Monitor in Hard X-Rays and Soft Gamma-Rays with Wide- Field Gamma-Ray Telescope «Gammascope» Skobeltsyn Institute of Nuclear Physics, Moscow State University.

Scientific objectives: Temporal phenomena in hard x-rays and soft gamma-rays (0.05-1.0 MeV) X-ray Novaes and Transients Gamma-ray Bursts SGR Sky mapping Search of new sources: deep all-sky survey at the sensitivity level about an order higher than INTEGRAL IBIS Timing of X-ray and Gamma-ray sources Active Galactic Nuclei X-ray and gamma-ray pulsars NS and BH binaries

THE MAIN GOAL SIMULTANEOUS OBSERVATIONS OF GRBs IN OPTICS AND GAMMA-RAYS (AND HARD X-RAYS). THE WELL-OBSERVED OPTICAL AFTERGLOW IS INTERSTELLAR MEDIUM RESPONCE ON THE BURST WHILE THE OPTICAL AND GAMMA-RAY LIGHT CURVES OBTAINED FOR THE MAIN PHASE OF BURST GIVE THE CRUCIAL INFORMATION ABOUT CENTRAL ENGINE.

The basic instrumental principles: Coding-mask imaging telescope; Quasy-spherical (dodecaedron) configuration providing field of view about 2 sr; Module construction: 6 identical pentagonal mask plates and 6 PSD units. NaI-CsI active-shielded position-sensitive detector (PSD); Tungsten coding mask with pseudorandom pattern;

Goals: the adequate models of GRB central engine GRBs as the independent cosmological test determination of intrinsic bolometric luminosity in source LB determination of Eiso value, characterised the total energy release in source in the case of isotropic emission separation of GRB properties caused by physical processes in sources and those ones, which could be the sequence of cosmological time dilatation and photon softening. logN – logS distribution for low -intensive GRBs with S  10-7 erg/сm2 low S low kТ Low peack intensity The simultaneous optical and gamma-ray observations are crucial for central engine understanding!

Wide-field camera with objective blenda VIEW OF INSTRUMENTS: Gammascope instrument Wide-field camera with objective blenda

The scetch of Gammadcope instrument with sizes Coding mask and PSDs wide-field cameras

The view of “Gammascope” instrument The comparison of “Gammascope” sensitivity with other experiments

The number of detectable AGN-like sources versus TS ( in  sr, T in years, S in 1000 cm2)

The technical parameters of the “Gammascope” instrument: The total mass of the instrument; the mass of the detecting part of the instrument  160 kg  130 kg The applied power 95 W The day informativity  32 Мb Geometry factor 0.3 m2sr Angular resolution 2-3о Energy range 0.05 – 1.0 MeV Energy resolution (for 661 keV line)  15% Effective area ~500 cm2 Sensitivity for 106 s observation time ~30 mCrab

Technical parameters of gamma-detectors  15% Energy resolution (at 661 keV) 0.12 m2sr Geometry factor 2-3о Angular resolution 30 mCrab Sensetivity, for 106 sec ~500 sm2 Effective area 0.05 – 1.0 meV Energy range  32 Mb Informativity (per day)  95 Wt power  130 kg Mass Technical parameters of wide-field camera 20х40о Field of view up to 15 st. mag. Sensitivity level by superposition of images 13–14 st. mag. Sensitivity level for 0.2 – 0.3 s exposition  2 Gb Informativity (per day)  10 Wt Power  3 kg Mass

The laboratory model of Gammascope PSD

The Principle of Pixel Identification A) The sketch of PSD module construction B) The PMT signal amplitude versus the detecting crystal position. Dashed line is for the result of the calculations, solid line is for the approximation of measured values. Numbers under the X axis correspond to the NaI(Tl) crystal number (see (а))

for different variants of active shield logic: Energy dependencies of PSD efficiency for different variants of active shield logic: All interactions in NaI(Tl) and CsI(Tl) are detected; The gamma-quanta inside the FOV are detected if the energy lost in NaI(Tl) is greater than in CsI(Tl) shield; The gamma-quanta inside the FOV are detected if the energy lost in CsI(Tl) is zero; The gamma-quanta outside the FOV are detected if the energy lost in NaI(Tl) is greater than in CsI(Tl) shield; The gamma-quanta outside the FOV are detected if the energy lost in CsI(Tl) is zero;

PSD module. NaI(Tl) and photomultiplier positions are showen. Energy spectrum of Am241, measured for central position of detecting NaI(Tl) crystal. Е  60 кэВ E  30 кэВ PSD module. NaI(Tl) and photomultiplier positions are showen.

The dependence of the part of the light produced in NaI(Tl) collected by the PMT on the distance between the detecting crystal and the photomultiplier’s center. Thin lines show the value of the energy resolution (measured with Am241 (E=60) isotope. The dependence of the value of energy resolution on the distance between the detecting crystal and the photomultiplier’s center measured with Am241 (E=60) isotope.

181Hf spectrum measured with the use of LaBr3:Ce 5х15мм

Energy resolution of LaBr3:Ce & CeBr3 crystals at various PMT voltage

Change of CeBr3 energy resolution after activation by neutrons

Example of event in gamma-ray telescope Results of PSD illumination by gamma-quanta for  = 0

The image of a point source The image reconstruction: Coding mask element The image of a point source (from 1 frame)

Coding mask segment from Tantalum

Error boxes for GRB with S = 10-4 erg/сm2 & kT = 100 keV.

The reconstructed image of three nearby sources with different brightness: the result of modeling of the sky scanning by the orbital motion (1 orbit)

The sky map reconstructed for the gamma-ray sources from HEAO-1 A4 catalog (3D relief and color map). Cyg X-1 Crab Sco X-1

The sky map reconstructed for the gamma-ray sources from HEAO-1 A4 catalog after the “whittening” of three brightest sources Sco X-1, Cyg X-1 and Crab. Detailed map corresponds to the Galactic Center region [250o,300o], [-50o,50o].

The sky image reconstruction as result of the modeling of a scan along the Galactic plane during 1 day (sources from INTEGRAL IBIS catalogue, 40-100 keV)

The laboratory model of wide-field camera

The super wide field camera objectives

Sky image obtained with wide-filed camera with 0.2 s exposition .