M. Balaskó is a pioneer in the application of neutron radiography techniques for engineering and industry related projects. He was born on June 15th 1944 in Budapest (Hungary) and studied at the Technical University where he graduated in the Department of Electrical Engineering in1974. He got his PhD in 1984 about the topic of "Qualification of epitaxial layers grown from liquid phase" before he changed that field towards the neutron research, in particular for radiography applications. Probably, it was his wife Erzsebet Sváb, a still active expert in neutron scattering, who pushed the interest into the neutrons direction?

At the 10 MW WWS reactor of Russian origin he started to built a neutron radiography facility in 1984, mainly based on a video camera system, a precursor of the presently very common detection systems. This system was very unique in the Eastern part of Europe where such kind of experimental infra-structure was rare and the access to Western components quite limited. The goal was dynamic radiography and the visualization of two-phase flow phenomena.
Since 1990, M. Balaskó qualified very professionally and consequently for all kinds of degrees in non-destructive testing according to national rules and to EN 473.

M. Balaskó was very active in the promotion of neutron imaging techniques and their practical application, predominantly for defect analysis (e.g. Hungarian army's helicopter blades, refrigerator operation failures) or material research (super critical water behavior with respect to heat and pressure). Therefore, he became member of several national, European and international boards like International Society of Neutron Radiology (1996-2010), Applied Vehicle Technology Panel (AVT) of the Research Technology Organization (RTO) in the NATO (2003-2008), ACADEMIA NDT International (2009 -today) and the Advisory Committee for Neutron Imaging for SINQ, PSI, Switzerland.

Based on his knowledge he also practiced many teaching activities such on Schools abroad, for supervision of PhD students and for IAEA trainees. Until today he is co-author of 213 published papers and owner of 7 patents.

Because of the preliminary shut-down of the Budapest reactor M. Balaskó had to move his equipment and he succeed to establish new setups at the ASTRA research reactor in Seibersdorf/Austria (1987), and at the Maria research reactor in Swierk/Poland (2001). After the upgrade in Budapest, he reinstalled and improved the neutron radiography system again.

His emphasis was on the comparison of the results of radiography methods to other non-destructive testing methods as vibration diagnostics, acoustic emission, thermo vision, ultrasonic and liquid penetration.

What is to highlight most: M. Balaskó has been pioneering in film-free neutron imaging, in particular with dynamic options. He built one of the first imaging facilities in Europe under complicate conditions. He established very early the close link to industry and to engineering aspects. He managed to overcame difficulties in an Eastern country for collaboration and exchange of know-how before 1989. After "change of the system" Marton Balaskó became good moderator between East and West, e.g. transfer of the imaging device to Seibersdorf (A) and as active member of the COST action 524 about "Non-destructive testing using neutrons".

The idea of investigating neutron radiography first occurred to Dr. John Barton in December 1961 while attending a meeting in London on ways the wave properties of neutron radiation could be used, like X-rays, to study crystalline atomic structures in matter. He had recently joined the Applied Nuclear Science Faculty at the University of Birmingham and was supervising PhD students in such techniques. Neutron beam physicists would position their crystals using simple neutron absorbing markers and a film exposed to a scintillator screen converter. The vision of developing neutron radiography excited him for various reasons: the technology appeared much simpler than other neutron physics; the scope for benefits seemed essentially limitless over all future time; and, he thought he might have an original idea. The last thought was incorrect, of course, but in those days before computer search engines it took time to find that others had such ideas before, such as H. Kallman, 1937, and J. Thewlis, 1956. He was, however, alone in Europe in 1961. H.Berger and H. Watts worked in USA.

For the next thirty years Dr. Barton worked exclusively to help the international development of neutron radiography techniques and applications. To this end he devoted efforts as much to interesting others around the world to take up development of the field, as to undertaking individual projects. To remain focused on this one goal most effectively he moved his home between five locations in three countries from 1961 to 1981. During the initial three years, based at The University of Birmingham, he helped initiate interests at Harwell (reactor fuel applications), Aldermaston (research reactor utilization), Rolls- Royce Aero Engines (turbine blades safety), and Nuclear Enterprises (scintillators for neutron imaging). Before leaving Birmingham he ensured funding to help recruit Dr. Hawkesworth and others to continue development of neutron radiography. With a fellowship from the UK he then went to the Center for Nuclear Research in Grenoble, France. During nearly three years based in CEN Grenoble (1965-1968) important interactions included similar centers at Saclay, and Cadarache. He then moved to a base at Argonne National Laboratory from where during four years (1968-71) he again traveled extensively to help stimulate interest in centers for research or application nationally and internationally.

The International Neutron Radiography Newsletter, for which he was an editor, was one method to help the international development efforts during these early years. A compilation of 15 early issues from 1965 provides in its 210 pages a record of the centers in many countries that started activities during those early years and a listing of the reports prepared. In 1968 Dr. Barton raised through this communication the case for developing agreed methods to quantify the quality of neutron radiographic inspections, and this led to his initiation of an international committee to work on standards.

After the first ten years working exclusively to promote neutron radiography Dr. Barton organized a three day meeting of international exchanges held in Florida USA Dec 1971 and published in Transactions of the American Nuclear Society Vol. 12 No. 2 This contained 30 papers.

Between 1971 and 1978 Dr Barton was based at Oregon State University where access was available to a nuclear reactor with pulsing capability suitable for high-speed motion neutron radiography. Here too he was able to collaborate both nationally and internationally. The neutron radiographic inspection of mixed oxide (uranium-plutonium) nuclear fuel at Richland was important enough to justify installation of an on-site reactor facility. Another application, inspection of zirconium fuel cladding billets using a special cold neutron beam at a reactor, was recognized as the biggest single application to that time in the enlarging field of neutron radiography. One of much international collaboration was in Santiago, Chile where the International Atomic Energy Agency was providing an advanced center for nuclear capabilities.

In 1978 Dr. Barton moved again, this time to San Diego in Southern California. The move was to work with IRT Corporation on a diversity of neutron radiography applications including design of isotopic source systems using Californium 252. and early development of computerized axial tomography using neutron radiography. He later worked as consultant to assist with neutron radiography projects across the nation and across the world. Twenty years after committing to work exclusively toward international development of neutron radiography, Dr Barton organized and held in San Diego, what became known as "The First World Conference on Neutron radiography". The proceedings, published by D. Reidel. Contains 140 papers from 20 countries. Amongst those centers reporting activities were 5 from UK, 11 from France, 28 from the USA and nearly 100 from 17 other countries.

Dr. Barton helped organize and co-chair subsequent conferences in the series held in Paris 1986, Osaka, and San Francisco 1992 and at each the number of countries reporting progress has increased. The proceedings of the Fifth World Conference on Neutron Radiography includes an invited paper by Dr. Barton entitled "International Neutron Radiography-Past and Present. In that review more detail is provided including references to about fifty research papers authored by J.P Barton between 1964 and 1996 on various aspects of neutron radiography.

Between the 1992 conference and the 1996 conference Dr. Barton drafted a proposed constitution for the formation of the "International Society for Neutron Radiology" and co-ordinated review input from all co-founders. The foundation of the society was discussed and adopted at the 1996 conference. A paper entitled "International Society For Neutron Radiology-Foundation" is authored by JP Barton and included in the proceedings of the Fifth World Conference on Neutron Radiography published 1997 by DGZfP Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. ISBN 3-931381-08-0 edited by C.O Fischer, J.Stade, W.Bock.

International Symposia where Dr. Barton was honored to be the invited speaker on neutron radiography include Cambridge UK 1982 (The 50th anniversary of the discovery of the neutron), MIT USA 1983, Petten, Netherlands 1989, JAERI, Japan 1993, and Budapest, Hungary 1994.

Dr. Barton was born in London in 1934. He was educated in Physics at the University Of Birmingham, where there was a strong emphasis on nuclear physics. He then worked for four years with the UK Atomic Energy Authority first at Harwell then at Winfrith on theoretical and experimental design input for the UK nuclear power station program.

After retiring from neutron radiography work in 1992 Dr Barton has worked on some medical applications of neutron physics. He is also concerned with international efforts toward nuclear weapon control and disarmament.

He and his wife Claudia were married in 1965 in France. To follow his neutron radiography career she had to resign from a tenured position in Physics at the University of Grenoble. They live primarily at their home in San Diego but travel to UK, France and many other countries. They have two children and three grandchildren who live in northern California.

Harold (Harry) Berger is an applied physicist whose experience includes work, primarily in the field of nondestructive evaluation (NDE), with x-rays, gamma rays, neutrons, protons, infrared and ultrasound. His work with neutrons encompasses developments in neutron imaging, with film (direct and transfer methods), thermoluminescence, track-etch, image intensifier techniques and ionography. In the early 1960's he and his colleagues at Argonne National Laboratory (ANL) set up routine neutron radiographic transfer methods to inspect highly radioactive reactor components, a technique still used at nuclear centers. He and Dr. Gerold H. Tenney of Los Alamos National Lab arranged a 6-paper technical session on neutron radiography at the 1964 Fall Conference of the American Society for Nondestructive Testing (ASNT) in Philadelphia. Prof. Hartmut Kallmann, whose 1930's work on neutron radiography in Germany set the stage for later developments, attended the session at Berger's invitation. Prof. Kallmann, then of New York University, attended the session and contributed to the discussion. In response to the NR session discussion, Berger initiated the Neutron Radiography Newsletter in November, 1964 and served as Editor for the biannual Newsletter until the late 1960's, when Dr. John Barton took over the Editor position. Berger founded Industrial Quality, Inc. (IQI) in 1981 and served as President during the R&D company's 20 year run. As former Chief of the Office of Nondestructive Evaluation (NDE) at the National Bureau of Standards (NBS, now the National Institute of Standards and Technology, NIST), Berger initiated and directed the extensive NDE program at NBS (1975-1981). Before going to NBS in 1973 to set up a program in neutron radiography at the NBS reactor, Berger was a Senior Physicist and Leader of the NDE Group at ANL (1960-1973). He spent a sabbatical year from ANL working on fast neutron radiography at the Centre d'Etudes Nucleaire in Grenoble, France (1968-69) and as a Lecturer at the University of Grenoble. Earlier professional experience was with the General Electric Company (1951-1959) and Battelle Memorial Institute (1959-1960), working primarily on solid state detectors for x-rays and light. He currently is a consultant for the Digitome Corporation, working on volumetric x-ray imaging. Berger has B.S. (1949) and M.S.(1951) degrees in Physics from Syracuse University. He holds 12 U.S. patents and his technical publications number more than 200, including his 1965 book on neutron radiography (Elsevier), three ASTM books as Editor (including ASTM STP 586, "Practical Applications of Neutron Radiography and Gaging", the proceedings of an NR conference Berger organized at NBS, February, 1975) and more than 30 book and encyclopedia articles. Berger served as the first Technical Editor of the ASNT journal, Materials Evaluation, from 1969 until 1986. Honors include the rank of Fellow from the American Nuclear Society (ANS), ASNT, ASTM and the British Institute of NDT (BINDT) and as an Honorary Member of the Canadian Institute for NDE.  He also has additional awards from ANS, ASNT, ASTM, BINDT and the U.S. Department of Commerce. He was a Fellow-by-Courtesy at Johns Hopkins University Department of Materials Science & Engineering, 1986-2003. Berger presented the invited plenary paper at the International Topical Meeting on Neutron Radiography at Penn State University (June, 2001). He was a member of teams, whose work resulted in two "best products of the year" awards, the R&D-100 award (1965 for a operational neutron image intensifier and 1991 for a high density glass x-ray scintillator). Berger was a registered Professional Engineer (Quality Engineering) for more than 20 years.

When I started my first attempts in neutron radiography (with film methods) around 1994 there was a meeting of a European working group on Neutron Radiography, where American and Canadian partners were also be invited. It took place at BAM (Bundesanstalt für Materialprüfung) in Berlin for three days with about 10 participants only, among them Jack Brenizer. Other prominent persons of that meeting I remember were J. Domanus (Riso, Denmark), persons from Petten (Netherlands), Saclay (France) and C. Fischer (HMI Berlin). They all had already much more experience than me and I watched very carefully and with certain respect their presented details of studies. On a trip to USA, where I represented Switzerland in the program for the reduction in fuel enrichment for research reactors, about one year later, I met Jack a second time at his beam line of the Virginia University research reactor. I was very impressed by the radioscopy setup with video camera systems and light amplifiers in front. Unfortunately, this reactor was closed short time after including the beam line for the real-time inspection of materials there. This was the reason why Jack returned to his initial education site the Penn State University, where a professorship position was offered to him. At the same time, he got the access to a neutron imaging facility again because the reactor at Penn State continued running until today. Maybe, Jacks activities at that reactor, in particular for neutron imaging, have been a strong argument to maintain the operation on good level into the present time and in future. Later, we established a deeper contact for the preparation of conferences, exchange of knowledge and also performed private visits in both directions. In particular, he organized the “4th International Topical Meeting on Neutron Tomography in 2001 with great success at Penn State and published the proceedings in good time. Jack was very active in the approach to standardize and to advertise neutron imaging in the U.S. and on the international level by his own studies and memberships in related committees. Before he retired in 2016, he was in Oak Ridge active as advisor for the upcoming neutron imaging facilities at ORNL. I was always impressed by his enthusiasm and optimism, supporting students and co-workers with pleasure.

Eberhard Lehmann

Eberhard Lehmann was born in Leipzig in Eastern Germany on 16th July 1952 where he also studied physics graduating on the topic of “Molecular dynamic calculations of proteins” in 1974. He received his PhD at the East German Academy of Science in East Berlin in 1983 with his thesis entitled: “Cross-section data of construction materials for the fast breeder reactor by reactivity measurements”. In the years between 1976 and 1990 Dr Lehmann was active in research in reactor physics for fast breeders based on calculations of reactor parameters with different reactor codes and experimental work at different reactor stations in several countries of the Eastern hemisphere.

With the fall of the Berlin Wall and the Iron Curtain the Western world opened for the young physicist. He emigrated to Switzerland where he could apply his expertise and experience from 1991 to 1995 at the research reactor SAPHIR of the Paul Scherrer Institute.

1991 to 1995 as reactor physicist at the research reactor SAPHIR of the Paul Scherrer Institute. Given responsibility for core design and in particular neutron applications, he took his opportunity in the latter field and established the Swiss activities in neutron imaging starting in the mid 1990ties still at the SAPHIR reactor, which, however, was shut down in 1994.

As a reactor physicist without a reactor Dr Lehmann took his chances in the new spallation source project SINQ at PSI to establish neutron imaging at the new source. In an environment strongly dominated by neutron scattering, driving the source with applications of fundamental research in magnetism Dr Lehmann established a neutron imaging beamline, which became the reference for neutron imaging user service at large scale neutron sources in Europe and maybe even the world. Together with Burkhard Schillinger from TUM he introduced digital neutron imaging and tomography in Europe.

The user program at his neutron imaging instrument proved successful and Dr Lehmann was never tired to promote the technique nationally and internationally, to find fields of applications also beyond the main stream of non-destructive testing and established simultaneously a vivid scientific user program as well as a profitable service for industry.

He formed a group of experts contributing to nearly all fields of technical developments and applications as well as industrial service, which became a model for many state-of-the-art user instruments and imaging groups at large scale neutron sources as established today.

This included to add a second instrument dedicated to neutron imaging with cold neutrons just 10 years after the first one at SINQ. The new instrument ICON became a front runner in many modern developments utilizing monochromatic neutrons or other energy resolved techniques. Most notable grating interferometric imaging was pioneered by the ever growing group, which by the end of his career as an employee at PSI and group leader of the Neutron Imaging and Activation Group NIAG operated the two dedicated imaging beamlines NEUTRA and ICON, but also officially utilized up to 50% of two further instruments, BOA, a polarized testbeamline and POLDI, a time-of-flight diffractometer. In addition, his group is one of the driving forces and partners of the European Spallation Source (ESS) in establishing neutron imaging with a day-one instrument (ODIN) and to provide the software for imaging data analyses. Dr Eberhard also led his group from being a part of the Neutron Source Division to being a valuable and respected part of the Laboratory for Neutron Scattering and (now also) Imaging, which also underlines the successes in his time to prove the potential of neutron imaging not only for non-destructive testing but far beyond in material science and other fields of science, equivalent to (other) scattering techniques.

Dr. Eberhard Lehmann was not only in his active career a tiredless ambassador and forefighter of neutron imaging in particular at large scale facilities, an advisor to nearly all major imaging instrument projects at large scale sources but is still a very active and engaged member of the ISNR. After being a yearlong member of the board with the organization of the last world conference in Switzerland (WCNR-10, 2014) he became president and served between 2010 and 2014.

After his retirement in July 2017 he remains being an active member of the community, still serving on the ISNR board and as advisor in instrumentation projects, continuing his own research and being an ambassador of neutron imaging at large scale facilities.

Yoshiaki Kiyanagi is a pioneer in the development of pulsed neutron imaging and its application for engineering and material science.

He was born on January 1st, 1949 in Hokkaido (Japan) and studied at Hokkaido University, where he graduated from the Department of Nuclear Engineering in 1961 and got his PhD in 1993. He became an assistant professor, lecturer, associate professor and finally full professor of Hokkaido University. He had been the division head of the Nuclear radiation source engineering and educated many students and researchers. One of his contributions to scientific research is concerning the accelerator neutron source. He performed a lot of experiments at the Hokkaido University Neutron Source (HUNS) to obtain valuable experimental data which cannot be obtained by numerical simulations. With sufficient experimental data he has designed and developed a low-energy neutron moderation system. The ability of this system has been highly evaluated and employed by many institutes, like J-PARC in Japan, SNS of Oak ledge National Laboratory in the USA, and ISIS of Rutherford-Appleton Laboratory in UK.

He has developed the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) in the J-PARC. For this development, he won a technology development award from the Atomic Energy Society of Japan. He has also developed the pulsed neutron transmission spectroscopy, which gives spatial distribution of crystal structure in materials. For this development, he won a paper award from Japanese Society of Metals and Materials. Then he became a project leader to develop the pulsed neutron imaging facility (RADEN) in the J-PARC. The construction of RADEN was finished in 2014 and at present we can perform various kinds experiments at the J-PARC.

When he was a high school student, he began Japanese martial art, Kendo. Kendo is a traditional Japanese fencing. Normally we are using a Bamboo sword for practice instead of a real Japanese sword. So, he got great interest in the manufacturing process of the Japanese swords and started his investigation on the crystal structure of Japanese sword using pulsed neutron imaging. He is now Prof. Emeritus of Hokkaido University and Xian University in China, and President of Japanese Society for Neutron Science. He is still actively developing an accelerator neutron source for radiation therapy equipment at Nagoya University.

For his great contributions in our society, the honorable membership award was given to Prof. Yoshiaki Kiyanagi.

Professional Certification

PhD of Enginnering, Tokyo Institute of Technology, 1985.

Career

• Assiciate professor. Rikkyo University, -1992;
• Professor, Rikkyo University, -2001;
• Emeritus professor, Rikkyo University, 2001 (current).

Main activities

• Member of Executive Committee and Domestic Program Committee of The third World Conference, Osaka, (1989).
• Chairman of The Second International Topical Meeting on Neutron Radiography Systm Design and Characterizasion, Yokosuha and Editor of The Proceedings (1996).
• Member of Co-Chairman of The Third International Topical Meeting on Neutron Radiography, Lucerne (1998).
• Member of Organization Committee (Program Chairman) of The Sixth World Conference, Osaka, 1999. and Editor of "Neutron Radiography (6) Gordon and Brech (2001)".
• Member of Organizing Committee of The Sixth International Topical Meeting on Neutron Radiography, Kobe (2008).

Main works

He started research of neutron radiography using a handmade vertical collimator installed in the TRIGA-II reactor in Rikkyo University at 1984 [1]. After the success of the preliminary experiments a new versatile irradiation facility was installed in the No.2 tangential beam port of in the reactor, which have a changeable L/D value by using various diaphragm diameters (1 cm, 2.9 cm, 5 cm and 10 cm) and L value in the 4 m long shielded irradiation room [2. 3] at 1985. The port was also able to insert arbitrary filter materials at any desired position within the collimator sleeve.

When he had joined the neutron radiography group in the Second World Conference on Neutron Radiography, Paris, only a few papers were discussed quantitatively of the neutron images. Therefore, after the conference, he had been mainly interesting the basic science side, such as to establish how to quantitatively express and analyze an image, how to evaluate an inherent spatial resolution, how to determine a quantitative characteristics on neutron beam, and so on.
His first established study was simulation analysis of system transfer function (STF) of a screen-film system using a realistic Gd converter - X-ray film and the result were confirmed by experimental observation. The used parameters in the analyses were converter thickness, emulsion thickness, coating film thickness and a converter-film separation. As the fruit, the analysis concluded that the shape of modulation transfer function (MTF) was close to the Lorentzian shape, and the theoretical inherent resolution was evaluated to be 17 μm for the Gd-Kodak (SR-5) film system [4].
Since the beam quality was tested on the TRIGA II, he had extended the performance test for many facilities in World as well as in Japan. And he had measured the L/D and effective D values of such beams using the L/D device [5] (The Kobayashi Method [6]), and characterized quality of neutron beams, effective neutron energy, with various beam set up conditions using the Beam Quality Indicator (BQI) [7, 8]. The measured effective energies of beams using the BQI were summarized on elsewhere [9, 10, 11]. Various neutron beams were inspected in worldwide and inspected 63 beams were 9 beams for non-filtered facilities, 32 non-cooled filtered beams in the 16 facilities, one cooled filtered beam, and 5 neutron guide output beams [11]. It was strongly recommended that an undefined thermal neutron beam is not necessarily the same thermal spectrum and give image with the same quality. One of fruits of the BQI study was that effective energies of many thermal neutron beams were frequently shifted toward lower energy side using various filters, which were originally intended to reduce gamma ray background. It is proved that some beams were turn to good sub-thermal neutron beams.

Since the beginning of his research, many new imaging devices were developed and proposed, such as a dry film, several commercially available fluorescence materials including a pyrolytic boron nitrate plate [12], various imaging cameras, and so on. Among those imaging studies, a cooled CCD camera was the first applied to get neutron image at 1989 [3, 13]; the first CT image using the CCD camera was also obtained in 1992 [14]. Among the several CT studies, a statistical approach of quality evaluation of CT image was theoretically analyzed. The result proved that the statistical character is well explained by the log-transmittance (an integrated CT values along a projection line) [15].
New imaging methods were also proposed and preliminary tested such as a stereoscopic imaging [2], a new tomography technique using imaging plate [13], scattered radiation imaging [16], and an imaging using an alpha-Al₂O₃:C+Gd₂O₃ optical stimulated luminescent material [17].

A neutron sensitive photosimulated luminescence device (IP: imaging plate) was applied to neutron radiography in 1999. The performance was analyzed in details and proved that the material should become an excellent imaging device [18]. Basic performances of IPs were published elsewhere [19, 20], and the items studied performances were covered spatial resolution, linearity, dynamic range, statistical character, repeated readout characteristics, fading effects, responses for various radiation including alpha, beta, gamma and X-rays. The IP was proved excellent static imaging device for neutrons. It is well known that the IP is essential imaging tool today.

Among his research works, he summarized some requirements and basis of design for a future neutron beam facility [21], and also important parameters of relating image quality [22].

His studies were carried out mainly using the TRIGA-II Reactor in Rikkyo University (unfortunately the reactor was not operating and becomes into the decommissioning phase), and many experiments were implemented in the KUR in Kyoto University, and the JRR-3M in Japan Atomic Energy Agency (JAEA) in Japan.

References

[1]. H. Kobayashi et al., Neutron Radiography (2), 129-136 (1987)
[2]. H. Kobayashi et al., Neutron Radiography (3), 315-324 (1990)
[3]. H. Kobayashi, First Int. Topical Meeting on Neutron Radiography System Design and Characterization, Pembroke, 189-208 (1994)
[4]. H. Kobyashi, Neutron Radiography (3), 893-902 (1990)
[5]. H. Kobyashi and H. Wakao, Neutron Radiography (3), 885-892 (1990)
[6]. J. C. Domanus ed., Practical Neutron Radiography, (Kulwer Academic Publ., 1992) 123-126
[7]. H. Kobayashi and Y. Kiyanagi, Nucl. Instr. Method, A377 52-57 (1996)
[8]. H. Kobayashi, 5th WCNR-Berlin, 313-320 (1997)
[9]. H. Kobayashi and M. Satoh, Nucl. Instr. Method, A424 1-8 (1999)
[10]. H. Kobayashi, Neutron Radiography (6), 11-21 (2001)
[11]. H. Kobayashi, Applied Rad. Isotopes 61, 443-449 (2004)
[12]. H. Kobayashi et al., Neutron Radiography (4), 771-778 (1994)
[13]. H. Kobayashi et al., Neutron Radiography (3), 421-428 (1990)
[14]. H. Kobayashi, Nucl. Instr. Methods, A377, 80-84 (1996)
[15]. H. Kobayashi et al., Nucl. Instr. Methods, A424, 221-228 (1999)
[16]. H. Kobayashi et al., IEEE Trans. Nucl. Sci. 52, No.1, 375-379 (2005)
[17]. H. Kobayashi et al., IEEE Trans. Nucl. Sci. 52, No.1, 360-363 (2005)
[18]. H. Kobayashi and M. Satoh, Nucl. Instr. Methods, A424, 1-8 (1999)
[19]. H. Kobayashi, Neutron radiography (6) 271-278 (2001)
[20]. H. Kobayashi, et al., Applied Rad. Isotopes 61, 573-578 (2004)
[21]. H. Kobayashi, Neutron radiography (6) 169-176 (2001)
[22]. H. Kobayashi, Neutron radiography (6) 11-21 (2001)