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

WIND1994–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

SpectrometersLocalization 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 (2π 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 2π 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 4π 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-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, 2367Localization 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, 404-407

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 SGR1806-20 on December

27, 2004

Konus-Wind and Helicon (CORONAS-F) simultaneous observations of giant flare from SGR1806-20 on December 27, 2004

The full isotropic energy release Q=2,3х1046 erg and the peak luminosity L=3,5х1047 эрг с-1 (Frederiks et al., Astronomy Lett., 2007)