GammaRay and Relativistic Electron Flux Shorttime Variations Observed
Gamma-Ray and Relativistic Electron Flux Short-time Variations Observed in Vernov and Lomonosov Missions M. I. Panasyuk, S. I. Svertilov, V. V. Bogomolov, G. K. Garipov, V. O. Barinova, A. V. Bogomolov, A. F. Iyudin, V. V. Kalegaev, M. A. Kaznacheeva, V. S. Morozenko, I. N. Myagkova, P. A. Klimov, V. L. Petrov, A. V. Prokhorov, I. V. Yashin Skobeltsyn Institute of Nuclear Physics, Moscow State University. Moscow, Russia Physical Department of Moscow State University. Moscow, Russia
Space experiment “Vernov” small satellite (M=283 kg) with “RELEC” experiment on-board was launched on 2014 July, 8 into a polar solar-synchronous orbit with perigee ~600 km, apogee ~800 km Scientific goals of the mission: 1. Electron precipitations 2. Electromagnetic phenomena in nearby space 3. Transient phenomena in atmosphere
Instrumentation: § DRGE-1 and DRGE-2 – two identical detector boxes for x-ray and gamma-ray measurements with high sensitivity and good temporal resolution § DRGE-3 – contains three axe directed detectors of electrons, protons and gammas. § Telescope-T (MTEL-2) – optical imager. § DUV – detector of UV and optical flashes § NCh. A – low-frequency analyzer § RCh. A – radiofrequency analyzer § BE – information unit ~50 Gb of scientific data from “RELEC” complex were obtained during the period from 25. 07. 2014 to 10. 12 2015
DRGE-1 and DRGE-2 gamma-ray detectors There are two identical detector boxes named DRGE-1 and DRGE-2. Each of them consists of two identical detector units. These units made in one case work independently. Total area is ~500 cm 2 Detector consists of optically coupled thin (3 mm) Na. I(Tl) and considerably thick (17 mm) Cs. I(Tl) crystals. Thickness of Na. I(Tl) is optimized for soft part of energy range. Cs. I(Tl) plays a role of active shield for soft radiation being the main detector for hard one. Working ranges are 0. 01 -0. 5 Me. V for Na. I(Tl) and 0. 05 -3 Me. V for Cs. I(Tl) one.
Structure of output data 1. Monitoring frames Contain number of events detected in wide energy channels separately for Na. I(Tl) and for Cs. I(Tl) 2. Event frames Contain detailed data: (timer value at the moment of detection, fast and slow ADC codes) for each of gammas detected during the frame time but not more than some fixed value (default is 800 for equator, 200 for regions of trapped particles) 3. Telemetric frames Contain a number of health parameters including total rate, number of timer counts, energy thresholds etc.
Methods of TGF search in “RELEC” data - Since atmospheric gamma-ray flashes are characterized by small durations (<1 ms) “event” frame data were used for their search. It should be noted that in Equatorial regions the record of all the events in the detector was made, while at high latitudes only about ~20% of events was passed in event mode for reasons of reducing the amount of data. - Since the spectra of TGFs are hard only the events with energy over 400 ke. V were considered in the search algorithm. - The requirement of coincident flash in two or more detectors was used as an additional criterion of significance (see below)
Imitations caused by cosmic rays The most of short increases satisfying the criterion were related to the registration of heavy charged particles of galactic cosmic rays which cause a significant flare of scintillators, PMTS and overloading sensitive input elements of electronic circuits. In this case, the device records the sequence of noise pulses of decreasing amplitude at intervals of ~10 μs (time event processing electronics) and a total duration of several milliseconds. To suppress imitations of bursts by particles an additional requirement was added to the criterion. The cases when a sequence of points on the graph of "energy – duration" shows a monotonous decline of the amplitude (no less than 5 such points in a row) were excluded. Example of TGF imitation by cosmic-ray proton with energy ~15 Ge. V
Criterion used for TGF search The candidate must satisfy one of two conditions: A)registration at least 5 energetic gamma-quanta in a time interval of 1 ms by at least two detectors B)registration at least 3 energetic gamma-quanta in a time interval of 1 ms by at least two detectors. These criteria are consistent with: On the equator: the simultaneous registration of event by two detectors at 12 level or by three detectors at 7 level. At high lattitudes: the simultaneous registration of event by two detectors a 8. 5 level or by three detectors at 5 level. In order to exclude the registration of increases caused by intense variations of background in the areas of trapped radiation an additional condition was used: average background rate should not exceed 1500 Hz.
The results of TGF search N Time, UTC 1 07. 08. 2014, 22: 20: 55 08. 2014, 00: 31: 07 16. 08. 2014, 13: 06: 55 18. 09. 2014, 10: 15: 34 02. 11. 2014, 03: 34: 14 2 3 4 5 Detectors 1234 ++-+ Latitude, longitude 26. 2 W, 35. 6 N Duration (mcs) Notes 800 Number of quanta 10 +-++ 132. 04 E, 29. 4 N 1000 12 candidate 0+++ 114. 7 E, 24. 2 N 800 10 candidate +-0+ 160. 4 Е, 8. 3 N 400 31 TGF +0++ 40. 7 E, 77. 6 S 2300 18 candidate TGF
TGF 2014 -09 -18 -10 -15 -34 Gamma-radiation in DRGE-1(2) Electrons in DRGE-3 Sum for 50 mcs Energy loss spectrum in DRGE-1(2)
Time profiles of TGF candidates 2014 -08 -07, 22: 20: 55 2014 -08 -08, 00: 31: 07
Time profiles of TGF candidates 2014 -08 -16, 13: 06: 55 2014 -11 -02, 03: 34: 14
Comparison with the lightning activity according to the global network WWLLN A list of the closest lightning in a radius of 15 degrees from the subsatellite point (1500 km) Time Latitude, longitude 2014 -08 -07, 22 -20 -55 26. 2 W, 35. 6 N 2014 -08 -08, 00 -31 -07 Notes Т(before) / Т(after), WWLLN, (s) TGF 2954 / 16698 132. 04 E, 29. 4 N candidate 1/1 2014 -08 -16, 13 -06 -55 114. 7 E. 24. 2 N candidate 1/4 2014 -09 -18, 10 -15 -34 160. 4 E, 8. 3 N TGF 42 / 14 2014 -11 -02, 03 -34 -14 40, . 7 E, 77. 6 S candidate 87867 / 1736 WWLLN detects reliably only the stormy areas. If there is a thunderstorm then the distance between adjacent lightning is within a couple of seconds. The average duration of a thunderstorm is about 30 minutes, and the average size is of order 100 km. For this reason, on the area of several thousand square miles some storm is usually present and the distance between the lightning is within a couple of seconds
Next step of TGF search - New method of cleaning data from TGF imitations by particles, based on more accurate analysis of the time profile of candidate was realized. It allows to conduct a search of TGF according to the individual detectors (without coincidence). This will increase the analyzed observation period of almost 2 times - We plan to search with shorter times (~500 mcs) at the equator and at high latitudes at the level defined statistical confidence - We plan to compare both the previous and newly selected candidates with RFA data with ~100 ms temporal resolution , WWLLN, and other ground-based lightning networks. Some candidates obtained as a preliminary result of selection of 6 events for 600 μs from the detector DRGE-1 without coincidences
Map of 111 new TGF candidates from detector DRGE 11 for 294. 5 h out of ERBs and polar caps
Expected number of random events for all time of observation The figure shows the dependence of the expected number of random candidates on the selection parameter, expressed by the number of counts detected over 0. 4 ms. This dependence is calculated by multiplying the probability of accidental imitation on single interval (defined by Poisson distribution for taken background level), at the observation time.
Comparison with UV flashes UV data are obtained by DUV for 42 of TGF candidates, 2 events were accompanied by UV flashes
Distribution on time interval between TGFcandidate and previous/next lightning detected by the global network WWLLN
“LOMONOSOV” SPACE MISSION Was launched 28/04/2016 Ø Study of ultra-high energy cosmic rays Ø phenomena in hard x-rays and soft gamma-rays (0. 01 -3. 0 Me. V) Ø Search and detection of optical transients accompanying gamma-ray bursts Ø study of transient luminosity events in the Earth atmosphere Ø magnetosphere physics research
Parameters of “Lomonosov” mission: Orbit: ~500 km, polar Mass: spacecraft ~600 kg, payload ~150 kg Total power ~ 300 W Data amount ~3 Gb/day Launch date – 28/04/2016 Complex of instruments: • BDRG – gamma spectrometer • SHOK – wide field optical camera • UFFO – coding mask x-ray telescope + UV telescope • TUS – Telescope for detecting flashes in atmosphere produced by cosmic rays with E>5*10^19 e. V and TLEs • DEPRON, ELFIN-L – particle detectors
Instrument BDRG onboard “Lomonosov” BDRG instrument consists of 3 similar detector boxes, connected to data analysis box. Parameters of each BDRG box: Detector: 3 mm Na. I(Tl) /17 mm Cs. I(Tl) Sensitive area: 130 mm Energy range: 0. 01 – 3 Me. V Mass: 5. 5 kg Power consumption of detector box: <3 W Power consumption of data analysis box ~15 W Sensitivity for GRBs 10 -7 erg/sm 2 GRB localization- ~2 о for bright GRBs Goals of BDRG: 1. Production of GRB trigger 2. Spectral measurements and timing of GRB in hard x-ray and gamma range 3. Estimation of GRB coordinates 4. X-ray and gamma-ray monitoring 5. Study of TGFs
Accuracy of GRB localization from BDRG data: Dependence on fluence, k. T and background rate (the results of Geant numeric modeling) Standard formula for cosine shape of FOV: Here cos 1 , , cos 2 and cos 3 are cosines of the angles between the axis of correspondent BDRG box and the GRB direction. k. T=100 ke. V
Structure and amount of information from BDRG 3 detector boxes Type of frame Monitoring Spectrum Event mode Time interval between frames Data amount, Mb CONTINUOUS (180 MB PER DAY) 100 ms 87 per day 15 s 48 per day 15 s 50 per day BURST MODE FOR FAST/SLOW BURST (5 MB PER BURST) Monitoring 1 -10 ms 1. 6 per burst Spectrum 1 -10 s 1. 6 per burst Event mode Not regular, up to 106 events 1. 6 per burst Now the day portion of BDRG data is about 500 -1000 Mb
BDRG flight monitoring data More than 85% of time all 3 detectors of BDRG are operating More than 90% of time all types of data frames are collected
BDRG flight test: detailed spectral data
BDRG flight test: data for GRBs noted in GCN The event number 1 2 3 4 5 6 7 Type SGR SGR SGR GRB Date 18. 6. 2016 20. 6. 2016 23. 6. 2016 26. 6. 2016 03. 7. 2016 05. 7. 2016 Time Start 20: 27: 24 15: 16: 34 21: 20: 45 21: 23: 35 13: 54: 29 12: 10: 02 17: 40: 19 Time End 20: 27: 24 15: 16: 34 21: 20: 45 21: 23: 35 13: 54: 30 12: 10: 50 17: 40: 21 Total duration, s (T 90, s) 0. 1 0. 207 (0. 167) 0. 5 0. 1 0. 8 42. 8 (34. 2) 3. 4 (2. 6) Time resolution available, s 0. 1 0. 001 0. 1 0. 1 minimal channel, ke. V 10 -20 10 -20 35 -60 maximal channel, ke. V 60 -100 100 -170 170 -300 Best illuminated BDRG box BDRG 2 BDRG 1 BDRG 2 BDRG 3 Count rate /0. 1 s 20 -35 ke. V 287 451 274 236 378 10 17 Count rate /0. 1 s 35 -60 re. V 156 238 156 94 227 12 15 count rate /0. 1 s 60 -100 ke. V 34. 0 67. 1 49. 6 35. 7 66. 3 13 18 count rate /0. 1 s 100 -170 ke. V 0. 00 4. 99 3. 06 0. 97 3. 98 9 12 (20 -35)/(60 -100) in peak 8. 44 6. 72 5. 51 6. 62 5. 70 0. 77 0. 94 (20 -35)/(60 -100) for total 8. 44 7. 03 7. 81 6. 62 5. 68 0. 95 0. 32 Fluence in 20 -170 ke. V range, erg/cm 2 3. 0 E-07 9. 5 E-07 1. 5 E-06 2. 3 E-07 3. 3 E-06 5. 9 E-06 5. 4 E-07
List of GCN notices and BDRG events (5 SGRs, 11 GRBs)
BDRG: examples of light curves SGR 2016 -06 -23 GRB 2016 -07 -20 GRB 2016 -07 -05
SGRs in monitoring data with time resolution 0. 1 s
SGR LIGHTCURVES (“Monitoring”, time resolution 0. 1 s)
SGR LIGHTCURVES (“Monitoring”, time resolution 0. 1 s) The
SGR LIGHTCURVES (“Monitoring”, time resolution 0. 1 s) The
SGR LIGHTCURVES (“Monitoring”, time resolution 0. 1 s)
SGR LIGHTCURVES (“Monitoring”, time resolution 0. 1 s)
Light curve of SGR outburst measured 2016 -06 -20 by BDRG onboard “Lomonosov”
SGR JUNE 20, 2016 LIGHTCURVES (“Events”, time resolution 0. 01 s) Events in Na. I(Tl) in different energy ranges
FOURIER ANALYSIS OF SGR JUNE 20, 2016 To be discussed…
Detailed study of GRB 2016 -07 -20
Detailed study of GRB 2016 -07 -20 BDRG-2/Lomonosov GBM/Fermi
Observation of Solar Flare 19 -06 -2016 (C 1. 7 class)
BDRG monitoring data in RB and polar region
Detailed BDRG monitoring data near the RB
Detailed BDRG monitoring data: structure of RB
BDRG monitoring data: variations in the Equatorian region
Detailed BDRG monitoring data: variations in the equator region
Search of TGFs in BDRG/Lomonosov data 1) Triggering for TGFs – 10 ms trigger, coincidence of at least 2 detectors, energy range E>300 ke. V at the level >5 events, 10 sigma. Detailed event-moda data and 1 ms monitoring are formed 2) Off-line search in recorded event-mode data – will be realized soon. The instrument must be reconfigured for data amount optimization. Now some amount of event-mode data from triggers is collected to start the search
Thank You!
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