1. Normal text - click to edit 1 Corsica - 2008 N. Ostgaard 1, J. Stadsnes 1, P. H. Connell 2 T. Gjesteland 1 1) Department of Physics and Technology, University of Bergen, Norway 2) Institute of Mechanical Science, University of Valencia, Spain Monte Carlo Simulations of the temporal behavior of Terrestrial Gamma ray Flashes, and analysis of the BATSE measurements

2. Normal text - click to edit 2 Corsica - 2008 Outline Monte Carlo simulations –Time delay BATSE –Calculate the deadtime losses Compare MC time delay with BATSE measurements, which has low deadtime losses

3. Normal text - click to edit 3 Corsica - 2008 60 km altitude20 km altitude MC start with a 1/E energy spectrum Compton scattering changes the energy spectrum Monte Carlo simulation

4. Normal text - click to edit 4 Corsica - 2008 Monte Carlo simulations Compton scattering reduces the energy and increases the path length. Assumption: -High energy photons arrives at a satellite detector before low energy photons

5. Normal text - click to edit 5 Corsica - 2008 Hard: E>300 keV Soft : E<300 keV hardsoft 25 km altitude Time delay

6. Normal text - click to edit 6 Corsica - 2008 Time delay in previous studies: Hard: E>110 keV Soft: E<110 keV Nemiroff et al 1997 100-200 μs time delay Feng et al 2002 ~100 μs time delay BATSE measurements shows larger time delays Average 81 μs time delay

7. Normal text - click to edit 7 Corsica - 2008 A paralyzable detector m n The deadtime, τ, is found from the peak Counts per time

8. Normal text - click to edit 8 Corsica - 2008 Highest count rate in a single LAD: 5 cnt/10µs Deadtime ~0,725 µs

9. Normal text - click to edit 9 Corsica - 2008

10. Normal text - click to edit 10 Corsica - 2008 How many photons hits one BATSE LAD? R 2 –effect ~1,78 Effective area BATSE LADs –Total 2000 cm 2 –502 cm 2 (Grefenstette et al 2008) Effective area RHESSI –Total 250 cm 2 –239 cm 2 (Grefenstette et al 2008)

11. Normal text - click to edit 11 Corsica - 2008 Max RHESSI count rate (Grefenstette et al 2008) -0.056 cnt/(50 µs * effective area) ~ 13 cnt/ 50 µs Mean RHESSI TGF contains 26 photons (mean duration 1 ms) -Assume 26 photons during 0.26 ms -RHESSI average ~ 1 photon per 10 µs RHESSI photons/10µs2510 BATSE photons/10µs 500 cm 2 effective area71837 BATSE photons/10µs 1000 cm 2 effective area143774

12. Normal text - click to edit 12 Corsica - 2008 How many photons hits one BATSE LAD? < 15 photons / 10 μs

13. Normal text - click to edit 13 Corsica - 2008 3 types of TGF Long duration bursts- excluded Multi peak TGF are separated into single peaks BATSE time profiles

14. Normal text - click to edit 14 Corsica - 2008 All 8 LADs count rate ≤ 3 cnt / 10μs E>300keV E<300keV Milli sec Calculate the Time delay for each peak

15. Normal text - click to edit 15 Corsica - 2008 Average 55 μs time delay Average deadtime loss Deadtime % 0.7 μs13,2 0.8 μs14,6

16. Normal text - click to edit 16 Corsica - 2008 Conclusions MC-simulations: ~ 40 μs time delay for TGF produced below 25 km altitude. MC-simulations gives no time delay above 25 km The ”smal” BATSE peaks: ~55 μs time delay on average The time delay indicates that TGF are produced below 25 km altitude Deadtime ≤ 1 μs BATSE is most likely not total paralyzed Smal TGF <15 % losses due to deadtime.