1. 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.

2. Scientific objectives:
Temporal phenomena in hard x-rays and soft gamma-rays ( 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

3. 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.

4. 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;

5. 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!

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

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

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

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

11. 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

12. 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

15. The laboratory model of Gammascope PSD

16. 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))

17. 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;

18. 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.

19. 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.

23. 181Hf spectrum measured with the use of LaBr3:Ce 5х15мм

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

26. Change of CeBr3 energy resolution after activation by neutrons

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

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

29. Coding mask segment from Tantalum

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

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

33. 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

34. 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].

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

36. The laboratory model of wide-field camera

37. The super wide field camera
objectives

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