NIF Neutron Bang Time Detector Development on OMEGA

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1 NIF Neutron Bang Time Detector Development on OMEGA NBT2 scintillator bang time (ps) rms = 54 ps V. Yu. Glebov University of Rochester Laboratory for Laser Energetics NTD bang time (ps) 46th Annual Meeting of the American Physical Society Division of Plasma Physics Savannah, GA November 2004

2 Contributors C. Stoeckl, T. C. Sangster, C. Mileham, and S. Roberts Laboratory for Laser Energetics University of Rochester R. A. Lerche Lawrence Livermore National Laboratory

3 Summary NIF neutron bang time detector prototypes have been developed and tested on OMEGA The neutron bang time detector (NBT) diagnostic requirement for the NIF is better than 100-ps accuracy over a yield range from 10 9 to DD and DT neutron yield. The proposed solution is a three channel system based on a fast scintillator and CVD diamond detectors. Prototypes tested in DD and DT implosions on OMEGA show better than 100-ps timing accuracy, satisfying the NIF specification. E13527

4 A neutron bang time (NBT) detector is a core/facility diagnostic for the NIF The most important requirements developed by the expert group for the NBT on the NIF are the distance from TCC (~ 50 cm), the minimum neutron yield ( ), bang time accuracy ( 100 ps for DD and DT), and dynamic range (10 9 to ). The NIF NBT prototype has been developed and tested on OMEGA, satisfying NIF specifications. E13129a

5 The conceptual design of the NIF NBT prototype housing is simple; it should be able to work at TIM/DIM Light-tight thin aluminum cylinder for the scintillator + PMT Tungsten alloy shielding with removable front plate Two CVD diamonds inside the tungsten shielding W CVD1 MCP PMT Scintillator SHV SMA CVD2 HV cable Signal cable Al E13412

6 Two scintillator and three CVD-diamond prototypes were tested in re-entrant tubes in the OMEGA target chamber NBT1 scintillator channel 11-mm-diam, 3-mm-thick BC-422Q (1%) scintillator Hamamatsu R3809U-52, PMT with two MCP s, 140-ps rise time PMT gain of 10 5 and neutral density filter ND = 1 (attenuation 10) NBT2 scintillator channel 17-mm-diam, 3-mm-thick BC-422 scintillator Photek 113, PMT with one MCP, 150-ps rise time, gain 1000 CVD diamond channels CVD1: 10-mm-diam, 1.0-mm-thick wafer CVD2: 5-mm-diam, 0.3-mm-thick wafer CVD3: 2-mm-diam, 0.5-mm-thick wafer Scintillators and CVD diamonds were at 75 cm from TCC. E13413

7 Several different detector housings were tested in the reentrant tube on OMEGA for the NIF NBT prototype E13133

8 The infrastructure of the existing LLE NBT detector was used for the NIF NBT prototype tests Neutron bang-time detector RSI, 73, 3796 Target chamber Neutrons Implosion target Three-channel detector assembly Master oscillator Typical of 60 OMEGA beams Seed pulse for amplification and splitting Main laser modulator Amplifier section Tripler Sample of beam P510 UV streak camera Oscilloscope Photodiode E11451b Timing fiducial pulse train

9 It is possible to calibrate scintillator and CVD diamond channels using a 100-ps laser pulse on a gold target Signal (V) Signal (V) E Laser Laser NBT1 Shot Fit Fit Shot CVD Time (ns) 10 NBT1 calibration delay (ps) NBT1 x-ray calibration rms = 5 ps Shot number

10 The results from the single-stage MCP PMT prototype demonstrate its feasibility for the NIF Shot 36100, DD, Y n = Scintillator channel CVD diamond channel Signal (V) Signal (V) Time (ns) Time (ns) E13145 When scaled to 50 cm from TCC and with a DD neutron yield of , the scintillator channel of the NIF NBT2 will give a 260 mv signal.

11 Both scintillator and CVD diamond channels have a bang time accuracy better than 100 ps NBT2 scintillator bang time (ps) NBT2 scintillator versus NTD comparison rms = 54 ps CVD1 diamond bang time (ps) CVD1 diamond versus NTD comparison rms = 59 ps NTD bang time (ps) NTD bang time (ps) Bang time data Function Y = X E13508

12 The internal bang time precision of the NIF NBT prototype CVD diamond channels is about 15 ps Shot 37591, DT, Y = Signal (V) Signal (V) CVD1 CVD2 CVD1 CVD2 (ps) CVD1 CVD2 rms = 13.6 ps Shot number E13509 Time (ns)

2-mm-diam, 0.5-mm-thick 1 Shot 37600, DT, Y = 7.

13 A very small CVD diamond detector will extend the NIF NBT yield range up to CVD3, 2-mm-diam, 0.5-mm-thick 1 Shot 37600, DT, Y = Signal (V) E Time (ns)

14 Summary/Conclusions NIF neutron bang time detector prototypes have been developed and tested on OMEGA The neutron bang time detector (NBT) diagnostic requirement for the NIF is better than 100-ps accuracy over a yield range from 10 9 to DD and DT neutron yield. The proposed solution is a three channel system based on a fast scintillator and CVD diamond detectors. Prototypes tested in DD and DT implosions on OMEGA show better than 100-ps timing accuracy, satisfying the NIF specification. E13527

High-Yield Bang Time Detector for the OMEGA Laser

High-Yield Bang Time Detector for the OMEGA Laser Introduction The time interval from the beginning of the laser pulse to the peak of neutron emission (bang time) is an important parameter in inertial