WO2013116795A1

WO2013116795A1 - Method and apparatus for very large acceptance gamma ray detector for security applications

Info

Publication number: WO2013116795A1
Application number: PCT/US2013/024524
Authority: WO
Inventors: Robert Abrams; Kevin BEARD
Original assignee: Muons, Inc.
Priority date: 2012-02-01
Filing date: 2013-02-01
Publication date: 2013-08-08

Abstract

In particular embodiments, a device and a method are disclosed that include means and steps for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector. The device and the method also include means and steps for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications.

Description

METHOD AND APPARATUS FOR VERY LARGE ACCEPTANCE GAMMA RAY DETECTOR FOR SECURITY APPLICATIONS

INVENTORS:

Robert Abrams, Ph.D.

Kevin Beard, Ph.D.

J. Cross-Reference to Related Application

[0001] This application claims the benefit of U.S. Provisional Patent Application No.

61/593,857, filed February 1, 2012, which is hereby incorporated by reference in its entirety, as if set out below.

//. Field of the Disclosure

[0002] The present disclosure is generally related to a gamma ray detector for security

applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost and, in particular, to a gamma ray detector for security applications with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector.

///. Summary

[0003] In a particular embodiment, a device is disclosed that includes means for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector. The device also includes means for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications. [0004] In another particular embodiment, a method is disclosed that includes steps for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector. The method also includes steps for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications.

IV. Brief Description of the Drawings

[0005] The following figures form part of the present specification and are included to further demonstrate certain aspects of the present invention. The present invention may be better understood by reference to one or more of these drawings in combination with the description of embodiments presented herein.

[0006] Consequently, a more complete understanding of the present disclosure and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear, wherein:

[0007] Figure 1 is a diagram illustrating an embodiment of an apparatus including means for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector and means for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications; and

[0008] Figure 2 is a flow diagram of an illustrative embodiment of a method including steps for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector and steps for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications.

V. Detailed Description

[0009] Illustrative embodiments of the present invention are described in detail below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure.

[0010] Particular embodiments of the present disclosure are described with reference to the drawings. In the description, common features are designated by common reference numbers.

[0011] Referring to Figure 1, a diagram illustrating an embodiment of an apparatus is depicted and indicated generally, for example, at 100. The apparatus 100 includes means for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector 110 and means for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications 120.

[0012] Referring to Figure 2, a flow diagram of an illustrative embodiment of a method is depicted and indicated generally, for example, at 200. The method 200 includes steps for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector 210 and steps for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications 220.

[0013] Attached herewith as an Appendix to this specification is a document describing more details about various illustrative embodiments, which Appendix to this specification is incorporated by reference as if set forth below. More details about various illustrative embodiments may be found by referring to the Appendix.

[0014] The present invention is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as those that are inherent therein. While the present invention has been depicted, described and is defined by reference to exemplary embodiments of the present invention, such a reference does not imply a limitation of the present invention, and no such limitation is to be inferred. The present invention is capable of considerable modification, alteration, and equivalency in form and function as will occur to those of ordinary skill in the pertinent arts having the benefit of this disclosure. The depicted and described embodiments of the present invention are exemplary only and are not exhaustive of the scope of the present invention.

Consequently, the present invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.

[0015] The particular embodiments disclosed above are illustrative only, as the present

invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of composition or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and intent of the present invention. In particular, every range of values (of the form, "from about a to about b," or, equivalently, "from approximately a to b," or, equivalently, "from approximately a-b") disclosed herein is to be understood as referring to the power set (the set of all subsets) of the respective range of values, in the sense of Georg Cantor. Accordingly, the protection sought herein is as set forth in the claims below.

[0016] The particular embodiments of the present invention described herein are merely

exemplary and are not intended to limit the scope of this present invention. Many variations and modifications may be made without departing from the intent and scope of the present invention. Applicants intend that all such modifications and variations are to be included within the scope of the present invention as defined in the appended claims and their equivalents.

[0017] While the present invention has been illustrated by a description of various

embodiments and while these embodiments have been described in considerable detail, it is not the intention of the Applicants to restrict, or any way limit the scope of the appended claims to such detail. The present invention in its broader aspects is therefore not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of Applicants' general inventive concept.

APPENDIX

DoE SBIR Phase I, FY2012 Release 1

COMPANY NAME:

MuPlus, Inc.

45 Jonquil Lane

Newport News, VA 23606

PROJECT TITLE: Very Large Acceptance Gamma Ray Detector

PRINCIPAL INVESTIGATOR: Dr. Kevin B. Beard TELEPHONE: (757) 269-5678

TOPIC: 3, SUBTOPIC: e

STATEMENT OF THE PROBLEM OR SITUATION THAT IS BEING ADDRESSED

Gamma ray detectors for security applications should have large acceptance, good energy resolution, directional sensitivity and moderate cost. The large acceptance detectors now in use have extremely poor energy resolution and almost no directional sensitivity.

Conventional detectors with good energy resolution are generally fairly small, so have only very small acceptance, and using a very large number of them becomes prohibitively expensive.

STATEMENT OF HOW THIS PROBLEM OR SITUATION IS BEING ADDRESSED

The technique we propose to determine both the gamma energy and direction is to use many layers of low-cost segmented plastic scintillator and/or scintillating aerogel alternating with planes of photodetectors. Multiple wells in the body allow the photons to initially interact deep in the volume to greatly improve the collection of the backward scattered photons. By using a very large volume and relatively low density, the detector allows the Compton scattered photons to travel far enough to provide good direction information. From their energies and the locations of the electrons, one can infer the direction and energy of the incident gamma ray. Its acceptance is thousands of times greater than that of a conventional detector.

WHAT WILL BE DONE IN PHASE I

We will perform simulations of the performance of a detector comprised of scintillators and position-sensitive photodetectors, working toward an optimized design of the whole detector, and provide specifications for the individual components. Based on that, we will design and simulate a relatively small prototype to be constructed and tested in Phase II.

COMMERCIAL APPLICATIONS AND OTHER BENEFITS

The detector can be used to detect smuggled nuclear weapons and nuclear materials at ports-of-entry and major cargo terminals. It could be carried in an airplane for aerial searches for radioactive materials. It might even prove useful to detect a signature of the passage of nuclear powered vessels and ships carrying nuclear cargos. It may also be used as an aid in examining unidentified radioactive waste and cargo. Its large size and good position resolution makes it an excellent tracker of cosmic ray muons, allowing entirely passive scanning of any container, no matter how well it is shielded.

KEY WORDS: gamma rays, tracking, nuclear detection, nuclear proliferation

SUMMARY FOR MEMBERS OF CONGRESS

A new type of gamma ray detector offers a promise of roughly a 1000-fold increase in sensitivity and directional capability for finding hidden nuclear materials. NARRATIVE SECTION

Very Large Acceptance Gamma Ray Detector

Table of Contents

Table of Contents 2

Proprietary Data Legend 2

Project Overview 3

Identification and Significance of the Problem or Opportunity, and Technical Approach 3

Identification and Significance of the Problem 3

Technical Approach 4

Anticipated Public Benefits 12

Technical Objectives 13

Phase I Work Plan 13

Phase I Performance Schedule 13

Provisional Phase II Work Plan 13

Related Research or R&D 14

Principal Investigator and other Key Personnel 14

Consultants and Subcontractors 14

References 15

Proprietary Data Legend

This proposal contains no proprietary data.

Project Overview

This proposal is to study a novel gamma ray detector concept based on a large, relatively low density volume containing a high density of next generation optical detectors, providing both directional information, energy resolution, and a very large acceptance.

Identification and Significance of the Problem or Opportunity, and Technical Approach

Identification and Significance of the Problem

Conventional gamma ray detectors sacrifice almost all directional information. Among conventional detectors, the best energy resolution is found in hyper-pure germanium detectors (HPGe) (Figure 2), while the best efficiency is in large inorganic scintillators such as sodium iodide (Nal) (Figure 1). Only the largest detectors can capture most of the Compton scattered photons; those that escape degrade the efficiency and quality of the data.

For illustration, G4beamline[l], a widely used tool to simulate the interaction of particles and photons with matter and based on Geant4[2], was used to simulate a beam of 100 1 MeV photons interacting with the largest readily available conventional gamma ray detectors, a 10x10" Nal (Figure 1) and a 7x7cm HPGe (Figure 2); photons are shown in green and electrons in red.

Both the Nal and HPGe detectors sacrifice essentially all directional information and are relatively slow devices; in both cases, some of the energy escapes.

If the individual Compton- scattered events could be recorded, both the direction and energy of the incoming photons may be determined. This requires a finely granulated detector with excellent timing; only the recent advent of extremely fast, large area, inexpensive photodetectors makes such a device possible. While the energy resolution will never approach that of HPGe detectors, the large volume of the detector will collect thousands of times more photons.

Figure 1: G4beamline simulation of 100 lMeV gamma rays entering a 10x10 inch Nal cylindrical scintillator on axis from the right.

Figure 2: G4beamline simulation of 100 lMeV gamma rays entering a 7 x 7 cm HPGe detector on axis from the right.

Technical Approach

To extract both direction and energy information from incoming gamma-ray photons in the -0.25-3 MeV range via Compton scattering, one needs to measure the individual scattered electrons. To resolve the electrons, one needs a resolution much finer than the mean free path of the scattered photons and a means of ordering the scattered events. By combining a very large (>m) size with a low density (<1 g/cm ), the position and time resolution requirements are greatly eased. The selection of size and density depends strongly on the parameters of the photodetectors.

Common plastic scintillator may be approximated by C with a density of 1 g/cm ; at the energies of interest the cross section is dominated by Compton scattering. This scintillator is suitable for better than 1 ns timing. Due to multiple scattering, it is unlikely that both the first scattered electron's direction and energy could be measured well enough to be useful, but if the locations, order, and energies of all the scattered electrons could be measured sufficiently, one ought to be able to reconstruct the energy and direction of the initial photon.

How well those quantities could be reconstructed will be limited by the time and position resolutions of the optical detectors and scintillators and determined by simulation in Phase I and by experiment in Phase II. Any reasonable design will trade off density and size for time and spatial resolution.

One of the design criteria is the thickness of the layers in the detector, to be determined by simulations in Phase I. Gamma rays are able to penetrate many layers of plastic, but the Compton electrons' ranges are energy-dependent and are in the mm range for the relevant energies. A plot of electron range in polystyrene, shown in Figure 3b, helps set the scale for the thickness of the layers. An electron with energy of 1 MeV has a range of about 5mm of plastic; while the range for the highest possible energy Compton electron from a 2 MeV photon is about 10mm.

Figure 3: Photon cross sections in C and Pb as a function of energy [3].

Electron KE fMeVj

Figure 4: Electron range of electrons in polystyrene and stopping power of polystyrene for electrons as a function of electron kinetic energy (data from NRC tables)

Requirements for the photodetectors will be defined in Phase I, as a result of simulations of the overall detector and backgrounds. We currently have two detector candidates, as described below. Extensive Geant4-based G4beamline simulations will be use to determine what are the most critical parameters and to optimize the overall design. We will also explore some hybrid designs, G4beamline has been used mainly for high energy physics applications, so the first step is to test and verify the appropriate low-energy physics. Next, the overall geometry and layout of the detector will be studied; once an optimum design has been chosen, the dependence of the performance on the parameters of the photodetectors will determined. A large background, mostly cosmic ray muons, must be considered, and possibly eliminated by veto counters, as well as dark and readout noise in the photodetectors.

We anticipate that the design of the photodetectors will be an iterative modification of those currently being developed for other projects. As the photodetectors evolve, so will the design of the large gamma-ray detector.

The concept for a Very Large Acceptance Gamma-Ray Detector (VLAGRD) is shown in Figure 5. It consists of a 4 m diameter x 2.54 m thick cylinder made from 200 layers of 0.5 inch plastic scintillator separated by thin layers of photodetectors. The low atomic number and modest density of the plastic allows a large mean path for photons, giving ample space for position, time, and angular resolution. The cylindrical geometry was chosen for simplicity and to illustrate the principle. The geometry can be varied to meet the application needs. The concept of boring holes in the detector to allow the incident gamma rays to penetrate into the center of the detector volume is illustrated by showing the results of two extreme cases: a VLAGRD without a bore hole and another with a 1 inch bore hole. Figure 5 illustrates 100 lMeV gamma rays entering a 4m x2.54m VLAGRD through a 1" bore hole. The left hand figure in Figure 5 shows how the gamma rays scatter as they move through the detector. The gamma rays lose energy as they undergo interactions. The gammas penetrate further into the forward hemisphere, but a significant number scatter backwards. All of the gammas are contained in the detector. The right hand part of Figure 5 shows a plot of the locations of the points at which Compton scattered electrons are produced by the gammas. This plot shows that the Compton-scattered electrons are confined to a region of approximately -700 mm < x < +600 mm and 500 mm < z < 2300 mm. This also shows the justification for employing a detector as large as 2.5 m deep and several m in transverse size.

Figure 6 compares the Compton electrons produced in a VLAGRD with a no bore and the one with a 1 inch bore, in which 10,000 1 MeV photons impinge on the axis of the bore hole. With no hole, about 30% of the events lose some fraction of their energy outside the VLAGRD, mostly in the backward direction. With the bore hole, only about 0.3% of the gammas lose energy outside of the detector. A realistic design, which considers the target distance, depth and width of field, and rate should lie somewhere in between these extremes.

Figure 5: G4beamline simulation of 100 lMeV gamma rays entering a 4 m diameter x 2.54 m thick VLAGRD on axis through a 1" hole from the right. The figure on the left shows the

An alternative to boring holes may be to cast the scintillator sheets on a mold that has protrusions corresponding to the holes in the sheets. trajectories of gammas as they interact in the detector. The right hand figure shows a plot of the of x-position (horizontal) vs z-position (axial) of the points at which Compton scattered electrons originate in detector The blue lines indicate the outer boundary of the detector.

5000 4000 3000 2000 1000 0 -1000 -2000

zEnn]

Figure 6: Simulation of 1000 1 MeV gamma rays entering from the right into a 4 x 2.54 m VLAGRD with and without a central 1" bore. Surrounding the VLAGRD is an idealized invisible closed cylinder to tabulate escaped photons. For the case with a central bore, the Comp ton-scattered electrons are shown as green dots; the escaped forward photons (-0.3%) in mauve, and no photons escape backward. In the case without a central bore, the Compton electrons are shown in red, no photons escape forward, and the backward escaped photons (-30%) are shown as turquoise points.

Figure 7 shows scatter plots of radial distance (r) vs time difference (t - to) for Compton- scattered electrons and kinetic energy of Compton- scattered electrons vs time difference. The time difference is the difference between the time a Compton scattering occurs (t) and the time of the first interaction that produces a Compton electron (t₀). The r vs (t - 1₀) plot shows that most of the secondary Compton scatters occur within 5 ns of the primary interaction, with some correlation. The kinetic energy vs (t - to) plot shows how the energy degrades as the gamma ray propagates. The strong peaking at times « Ins are due mainly to the high energy Compton scatters. There is a large spread in times for the very low energy photons (KE « 0.1 MeV). For (t - 1₀), there are no photons seen with energies > -0.02 MeV.

Figure 7: Compton electrons from a simulation of 100 1 MeV gamma rays entering a 4m diameter x 2.54 m thick VLAGRD in a 1" central bore; left shows distance to axis vs. time from 1^st interaction, while right shows kinetic energy vs. time from 1^st interaction.

Of course, any design hinges on the details of the photodetectors. We are examining a number of possibilities; two candidates are shown in Figures 8 and 9. For simplicity we show a rectangular geometry, suitable for a test setup. Figure 8 shows a section of a detector consisting of an array of plastic scintillator (or doped aerogel scintillator) plates arranged in planes that are stacked to form modules. Each plate has a silicon photomultiplier (SiPM) mounted directly and optically coupled to the scintillator plate. Such an arrangement has been tested as part of a calorimeter for high energy physics detectors [4]. There are several desirable attributes of this approach. The light produced in the scintillators is detected in each scintillator element. The entire detector is made of scintillator, except for the SiPM photon sensors. SiPMs are available from a number of industrial suppliers. SiPMs operate a low voltage (~ 50VDC) and a relatively low cost. SiPMs have good time resolution (~ few ns), well matched to the signals from plastic scintillators.

The planes closest to the source can have holes bored through the scintillator planes to allow some of the gammas to penetrate into the center of the array of planes in order to capture the backward-going products of the interactions of the gammas in the detector. We will evaluate the performance characteristics of this type of detector, and the required geometry and granularity of the detector, and the cost. The space resolution improves as the inverse size of the scintillator plates, and the cost increases with the number of SiPMs, which, in turn, depends on the number of layers (Figure 8).

The overall efficiency and number and arraignment of any bores is a question of optimization and depends on many factors, including the quality of the electronics and the reconstruction software; both need to be fairly sophisticated and the developing the details of both will be deferred until Phase II.

Hoies in scintillator

Figure 8: A conceptual version of a section of a VLAGRD, based on a large array of scintillators with a silicon photomultiplier (SiPM) attached to each piece of scintillator. Holes in the first set of scintillator planes allow gammas to penetrate deeper.

A further improvement in the detector is to utilize photo-detectors that are being developed as a new generation of fast, high-resolution large-area, low-cost micro-channel plates (MCPs), as shown in Figures 9 and 10. This type of detector is being developed by a collaboration of groups from universities, National Labs, and businesses [5]. These detectors are being designed for time resolutions that are <10ps and position resolutions -0.5 mm, both of which are better than we anticipate for our requirements, but relaxing both the time and space resolution requirements would reduce the cost of the associated electronics. We note that, in Phase I, we propose to do a feasibility study of using this type of detector. We consider that this concept may be more suitable for use in the future when this type of detector becomes available for use in this application.

A representation of a VLAGR using the MCP-like modules is shown in Figure 9. Planes of scintillator are alternated with planes of MCP photodetectors; light produced in the scintillators is converted to electrical signals by the MCPs. The scintillator planes need not be segmented into sub-units as in the first arrangement, but holes may be bored in the first layers of the scintillators as in the first arrangement. No holes need be cut into the MCP detectors themselves. Figure 10 shows a schematic representation of the functioning of the MCP element in its fast time resolution mode. In this example, but not in a VLAGRD, the entrance window is used as a Cherenkov radiator. The radiated photon hits a photocathode and produces a photoelectron that is multiplied in the MCPs, and the signal is collected at the anode plane, which is segmented to provide position resolution. In our application the light is produced in the scintillator, and the window is clear glass, necessary for maintaining a vacuum required for the MCP elements.

Figure 9: Concept of the VLAGRD based on large micro-channel plate (MCP)

photodetectors [6].

Figure 10: Schematic view of a MCP detector. The left-hand figure illustrates the principle of operation. Light produced in the radiator impinges on a photocathode. The

photoelectrons are multiplied in the pair of MCPs, and strike the anode. The right-hand figure shows an enlarged view, in which Cherenkov radiation is produced in the window for a charged-particle application. The Cherenkov radiator is not needed in this

application. (Figure courtesy of the LAPPD Collaboration.)

In Phase II, a portion (with a volume of at least several cubic feet) of a large gamma detector will be constructed, tested, and compared to simulations.

Anticipated Public Benefits

This proposal addresses an opportunity to develop a very large, relatively low cost detector. It would have an enormous acceptance for gamma rays, and could quickly detect and locate radioactive sources. The same detector may also serve as a relativistic particle tracker, for example, as a cosmic ray tracker to passively scan cargo containers, and could do both tasks simultaneously. With small modifications, it could also be used as a neutron detector, and would be very good at neutron/gamma separation. It could also be used as the detector with active interrogation systems, greatly reducing the require dose delivered to the cargo. Technical Objectives

Phase I Work Plan

The main purpose of the Phase I work plan is to develop a conceptual design for very large acceptance gamma ray detector with achievable large area photodetectors.

1. Test and improve the low-energy physics models used in the simulations.

2. Explore various designs and concepts, including hybrid designs using simulations.

3. Select a specific photodetector technology and partner with experts in that technology.

4. Develop software to convert the simulations output into input to the photodetectors.

5. Develop software to simulate the photodetectors responses.

6. Develop software to reconstruct the event and distinguish events from background.

7. Predict the overall detector response and resolution.

8. Prepare a proposal for Phase II to construct and test a prototype detector.

Phase I Performance Schedule

Three months after the start of funding:

1. Document the state of the physics processes in Geant4 and G4beamline

2. Develop a baseline design and select a photodetector technology

3. Begin simulations to determine the dependence on the photodetector parameters.

Six months after the start of funding:

1. Establish a partnership with a photodetector source.

2. Have software in place to convert the physics simulations into photodetector inputs.

3. Have software in place to estimate the photodetector response

4. Begin the reconstruction package

Nine months after the start of the funding:

1. Complete overall baseline detector design and performance

2. Begin the simulation and design of a prototype.

3. Prepare and submit Phase II proposal.

Provisional Phase II Work Plan

Although the Phase II work plan will depend on the results of the Phase I study, it is anticipated it will mostly focus on the design, construction and testing of a section of the overall detector. Related Research or R&D

The complete Muons, Inc. program is summarized in the Commercialization History document that is part of this proposal. Related projects that are associated with muon cooling and muon colliders are described there.

Muons, Inc. is currently a member of the LAPPD collaboration and is exploring other applications for these new photo-detectors, including using them for non-magnetic particle spectrometer systems and for cosmic ray muon scanning of containers.

Principal Investigator and other Key Personnel

Muons, Inc. Scientist and Principal Investigator: Dr. Kevin Beard earned his Ph.D. at Michigan State University's National Superconducting Cyclotron Laboratory and has participated in many nuclear experiments at a number of facilities. He has experience designing and using a variety of nuclear detectors and performed many of the early simulations for the Gammasphere detector. Prior to joining Muons, Inc., he worked the Jefferson Lab's Free Electron Laser, and has been a member of the muon collider collaboration for some years. He is an active member of the LIPSS dark matter search collaboration and wrote all the software to analyze the output of the CCD cameras used in that experiment. His office is at Jefferson Lab in Newport News, VA.

Muons, Inc. Scientist: Dr. Robert Abrams earned his Ph.D. at University of Illinois at Urbana- Champaign and has experience both in particle physics and in industry with AT&T Bell Laboratories and Lucent Technologies. He has special expertise with particle detector development.

Facilities /Equipment

Muons, Inc. currently shares facilities with MuPlus, Inc. This includes our corporate headquarters, a building of approximately 4000 square feet of floor space in Batavia, IL, a short drive from Fermilab, which is used as office space conference rooms, workshop area, and living quarters as needed. We also share office space with MuPlus, Inc. in Wilson Hall at Fermilab (Batavia, IL) and in the ARC building at Jefferson Lab (Newport News, VA). We have several high-performance personal computers and workstations with high-speed net access and sufficient computer power to perform simulations and CAD work.

The work in this proposal is to be performed in collaboration with Jefferson Lab, which is well known for its detector expertise.

Consultants and Subcontractors

We will have no consultants or subcontractors during Phase I. We expect, however, to add Jefferson Lab as a subcontractor during Phase II. Negotiations for this will occur during Phase I. A letter expressing their interest is attached to this proposal. References

[1] G4beamline: A "Swiss Army Knife" for Geant4, optimized for simulating beamlines, http://g4beamline.muonsinc.com

[2] http://geant4.cern.ch

[ 3 ] K. Nakamura et al. (Particle Data Group), J. Phys. G 37, 075021 (2010)

[4] A. Dyshkant, et al, "Directly Coupled Scintillator Tiles and Silicon Photomultipliers", Technology and

Instrumentation in Particle Physics 2011 (TIPP 2011) conference. See

http://indico.cern.ch/contributionDisplay.py?contribId=10&sessionId=24&confId= 102998

[5] The Large Area Psec Photodetector (LAPPD) collaboration includes major participation from the University of

Chicago and Argonne National Laboratory. Muons, Inc. is a participating member of the collaboration.

http://psec.uchicago.edu/.

[6] Large Gamma Detector Concepts, internal Muons, Inc. presentation, R.Abrams, 1/11/2012

Claims

1. A device comprising:

means for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector; and

means for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications.

2. A method comprising:

steps for providing a gamma ray detector for security applications with large acceptance, good energy resolution, directional sensitivity, and moderate cost, with the large acceptance being at least a thousand times greater than a conventional acceptance of a conventional gamma ray detector; and

steps for operating the gamma ray detector for security applications for at least one of detection of smuggled nuclear weapons and nuclear materials, being carried in an airplane for aerial searches for radioactive materials, detecting a signature of passage of nuclear powered vessels and ships carrying nuclear cargos, examining unidentified radioactive waste and cargo, and tracking cosmic ray muons allowing entirely passive scanning of any container, no matter how well the container is shielded, using a large size and good position resolution of the gamma ray detector for security applications.