The Konus-FG experiment for gamma-ray burst studies in GAMMA-400 M.V. Ulanov, R.L. Aptekar, D.D. Frederiks, S.V. Golenetskii, E.P. Mazets, and V.D. Pal’shin Ioffe Physical-Technical Institute, St. Petersburg, Russia

Historical remarks GRB research experiments:  KONUS / Venera 11–14 (1979–1983)  KONUS-WIND (1994–present time)  CORONAS-I, CORONAS-F, CORONAS- PHOTON (2001–2009) Autonomous localization:  GRANAT (1989)  KONUS-A / Cosmos-2326, 2367, 2421 (1995–2008)

Joint Russian-American Konus-Wind experiment WIND 1994–present time WIND orbit

Konus-Wind GRB Experiment  Two detectors S1 and S2 (NaI(Tl) 13cm diameter, 7.5cm height, Be entrance window). Placed on opposite faces of the spacecraft, observing the south and north ecliptic hemispheres of the sky.  Background mode: G1 (20–80 keV), G2 (80– 300 keV), G3 (300–1200 keV) with time resolution 1.47–2.94 sec.  Burst mode: time resolution 2ms–256ms, energy spectra (20keV–15MeV).

Scientific goals of the Konus-FG experiment  Detection and prompt (1–2 sec) localization of GRB sources in 10 keV – 3 MeV energy range with accuracy of 0.5–3°.  Localization information can be used for GAMMA-400 pointing to burst source or for further data analysis.  Study of temporal and spectral properties in 10 keV – 15 MeV range with two high- sensitive spectrometers.

Schematic diagram of the Konus-FG instrument Spectrometers Localization array of four detectors with anisotropic sensitivity

Konus-FG-DN: localization units The localization subsystem is formed by four identical detectors “Konus-FG-DN”, registering photons in 10–700 keV range. The detector’s anisotropic angular sensitivity is proportional to the cosine of the angle of incidence and is formed in the soft part of spectrum ~40– 160 keV. The axes of the DNs are offset from the symmetry axis by 30° and separated in azimuth by 90°. Field of view of each detector (2 π sr) should not be occulted by construction details of the telescope. The system provides burst localization in upper hemisphere within detector’s field of view (~75% of 2 π sr) that exceeds the effective angular aperture of the telescope.

Konus-FG-DS: spectrometry units The spectrometric subsystem includes two identical wide directional spectrometry detectors “Konus-FG- DS” operating in 10keV–15MeV energy range. The axis of the detectors should be pointed parallel to the main spacecraft axis that provides the survey of the whole celestial sphere 4 π sr. DS detectors obtain detailed information about energy spectra and time history of bursts. Konus-FG-DS will be a valuable part of triangulation network (IPN), which will improve the reliability and accuracy of automatic localization.

Location of Konus-FG units (preliminary) Konus-FG-DN Konus-FG-DS

The Konus-FG-DS detector unit The main parts of the detector: 1 – NaI(Tl) crystal 5’’ in diameter by 3’’ in height, 2 – beryllium entrance window, 4 – lead glass, 6 – photomultiplier, 12, 13, 14 – electronic boards.

The Konus-FG-DN detector unit The main parts of the detector: 1 – NaI(Tl) crystal 5’’ in diameter by 1’’ in height, 2 – beryllium entrance window, 3 – lead shield, 4 – lead glass, 6 – photomultiplier, 12, 13, 14 – electronic boards.

Konus-A / Cosmos 2326, 2367 Localization detector prototype  Each detector had 130 mm in diameter and 30 mm in height with the passive shielding on lateral side.  The axes of detectors are offset from symmetry axis by 30° and separated in azimuth by 90°.  The accuracy of localization is of 0.5 to 2–3 angular degrees depending on the burst intensity. R.L.Aptekar et al. ApJ 1998, 493,

Unsolved problems  Arrangement the optimal location of Konus-FG detectors on the GAMMA-400 spacecraft.

Broadband observations of the naked-eye gamma-ray burst GRB080319B

The ultra-luminous GRB110918A

Konus-Wind and Helicon (CORONAS-F) simultaneous observations of giant flare from SGR on December 27, 2004

The full isotropic energy release Q=2,3х10 46 erg and the peak luminosity L=3,5х10 47 эрг с-1 (Frederiks et al., Astronomy Lett., 2007)