Photofission for active SNM detection I: Intense pulsed 8MeV bremsstrahlung source

Hill, Cassie; O’Malley, J.; Ellis, M.; Mistry, Pritesh; Maddock, Robert C.; Precious, J.; Zier, J. C.; Jackson, S. L.; Hutcheson, A.; Mitchell, Lee J.; Phlips, Bernard F.

doi:10.1109/nssmic.2012.6551347

Cited by 7 publications

(12 citation statements)

References 5 publications

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“…As can be seen, there is no obvious attenuation trend in the data with only a small amount of variation between the different shielding configurations. This is fairly consistent with the Bremsstrahlung data obtained in March 2011 [2] where a clear dependence was not obvious, especially over the low mass thickness range (less than 20g/cm 2 ). In terms of overall signal, the approximate number of neutrons per cm 2 at 1m from the DU plate (for a bare shot) was approximately 2.…”

Section: Analysis Of Resultssupporting

confidence: 91%

“…Calculations performed in advance of the experimental setup revealed that the expected gamma yield above the 6MeV energy range required to induce photofission in depleted uranium (DU) was an order of magnitude lower than those seen in a previous experimental series performed using Bremsstrahlung x-rays [2]. In order to provide a suitable comparison between the two series, the conjugate distances were significantly reduced.…”

Section: Methodsmentioning

confidence: 95%

“…An example of dead-time in the 3He detectors is illustrated in In order to validate the other MCNPx modelling designed to aid understand the relative merits of a number of candidate sources, two experiments were chosen to be modelled using MCNPx and compared against the experimental data. The selected experiments were the characteristic gamma source and a nominally 8 MeV bremsstrahlung source [2], both with the same, unshielded, DU target. Fig.…”

Section: Detector Dead-timementioning

confidence: 99%

“…1= f S,(t)dt = nf ( -t. v,A,e-" )+C (2) The data has been normalised so that the shape of all three sources of data can be compared without accounting for magnitude. It can be seen that the experimental data and empirical 237 Np data agree very well, and that the MCNPX data has a similar, but none-the-Iess different decay shape.…”

Section: Detector Dead-timementioning

confidence: 99%

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Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)¹⁶O characteristic γ source

Mistry

Hill

O’Malley

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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An ongoing programme investigating the active detection of special nuclear material (SNM) is being undertaken by the Atomic Weapons Establishment (A WE) in collaboration with the Naval Research Laboratory (NRL). The programme is funded through the UK Home Office, Ministry of Defence and Cabinet Office and the Naval Research Laboratory supported primarily through the US Defence Threat Reduction Agency with support also from the Office of Naval Research and the Defence Nuclear Detection Office. The process by which the UK are applying active detection techniques to border protection and a review of the current challenges and opportunities for this technology as assessed by the authors is provided. As part of this programme, the NRL Mercury IVA was operated in positive polarity mode to produce photons characteristic of the 19 F(p,ay) 16 0 reaction, at energies of 6.13, 6.92 and 7.12 MeV. Protons produced by Mercury interact with a thick Teflon (PTFE) target to produce characteristic gamma radiation. These in turn were used to induce photofission in a depleted uranium (DU) sample. Eighteen experiments were fielded in September 2011, in which thirty-five detectors were fielded, including 3 He tubes, NaI detectors, liquid scintillators and high purity germanium detectors, capable of detecting both gamma radiation and neutrons. The results from a selection of those detectors are discussed here. A variety of high-Z (lead) and hydrogenous (borated polyethylene) and hydrogenous shielding configurations was employed and positive detection was made up to the maximum shielding tested, 8.Sg/cm2. Effects of secondary reactions in the photon production are visible in the results and some employed reduction techniques are discussed. Monte Carlo modelling has been employed for a subset of the 3 He tubes fielded. The resultshave been found to agree within an order of magnitude, but have also been found to die away more quickly than observed in the experimental data.

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Section: Analysis Of Resultssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 95%

Section: Detector Dead-timementioning

confidence: 99%

Section: Detector Dead-timementioning

confidence: 99%

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Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)¹⁶O characteristic γ source

Mistry

Hill

O’Malley

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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“…The second set concerned quantification of the output of interrogating neutrons from 7 Li(p,nfBe reactions with pulsed power generated proton sources. Results from these experimental campaigns are included in these conference proceedings [2,3,4]. objects Three important results were derived from these experiments in relation to the source optioneering question for a prototype active detection system.…”

Section: Empirical Evidencementioning

confidence: 99%

Active detection of special nuclear material - Recommendations for interrogation source approach for UK prototype active detection system

Hill

O’Malley

Martin

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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A WE is developing a prototype active interrogation system to enable robust detection of shielded nuclear material within the context of border choke point detection. This paper describes a study which took place in order to determine the optimum type of radiation and pulse structure to be used with the prototype system. A wide variety of neutron and gamma interrogation sources were considered including the use of sub 10 MeV end-point energy bremsstrahlung or 19F(p,uyi60 characteristic gamma sources and the use of DD, DT, and lower energy beam-target neutron sources such as those produced via. 7 Li(p,n) 7 Be. In each case, where appropriate, both flash systems capable of delivering intense, sub 100 ns pulses of radiation and non-flash repetitively pulsed or continuous wave (CW) sources were considered. Experimental measurements of photo-fission signatures on bare and shielded depleted uranium produced by 100 ns flash sources of 8 MeV bremsstrahlung and 19F(p,uyi60 characteristic gamma sources together with a systematic series of simulations of photofission signatures and associated backgrounds and a review of technological limitations of relevant accelerator technologies were all assessed.An estimate derived from experimental measurements of a minimum number of fissions necessary to detect target quantities of special nuclear material through shielding thickness of interest in the context of border detection is used to determine a charge which must be delivered by the interrogation source and this in turn is used to rank potential interrogation source options.Wider arguments concerned with the ease with which fission signatures may be discriminated above active backgrounds and the utility of different options given operational constraints are then presented and it is concluded that the UK will recommend a flash «100 ns), 10 MeV end-point energy bremsstrahlung source for the UK active interrogation prototype system.

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Mixed Source Interrogation of Steel Shielded Special Nuclear Material Using an Intense Pulsed Source

et al. 2015

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Photofission for active SNM detection I: Intense pulsed 8MeV bremsstrahlung source

Cited by 7 publications

References 5 publications

Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)¹⁶O characteristic γ source

Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)¹⁶O characteristic γ source

Active detection of special nuclear material - Recommendations for interrogation source approach for UK prototype active detection system

Mixed Source Interrogation of Steel Shielded Special Nuclear Material Using an Intense Pulsed Source

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Photofission for active SNM detection I: Intense pulsed 8MeV bremsstrahlung source

Cited by 7 publications

References 5 publications

Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)16O characteristic γ source

Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)16O characteristic γ source

Active detection of special nuclear material - Recommendations for interrogation source approach for UK prototype active detection system

Mixed Source Interrogation of Steel Shielded Special Nuclear Material Using an Intense Pulsed Source

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Product

Resources

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Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)¹⁶O characteristic γ source

Photofission for active SNM detection II: Intense pulsed 19F(p,αγ)¹⁶O characteristic γ source