CO12-1

Basic Research of an Intense Terahertz Light Source Based on
Coherent Cherenkov Radiation Matched to the Circular Plane

N. Sei and T. Takahashi1

Aluminium collimator
Ti window

Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial
Science and Technology
1
Research Reactor Institute, Kyoto University

Aluminium foil mirror

Electron beam
Hollow conical dielectric
Coherent Cherenkov
radiation matched thecircular plane

INTRODUCTION: One of the author proposed an
intense terahertz (THz) light source based on paralleledcoherent Cherenkov radiation (CCR) which was generated by a relativistic electron beam traveling through ahollow conical dielectric [1]. As superimposing coherent
diffraction radiation with many diffraction elements, theintense THz light can be generated by matching the CCR
to the circular plane. We report results of the preliminary
experiments of the CCR matched the circular plane(CCR-MCP).

EXPERIMENTS: We performed preliminary experiments of the CCR-MCP with an L-band electron linac at
the Kyoto University Research Reactor Institute (KURRI-LINAC). Figure 1 shows the schematic layout of the
CCR-MCP experiments. We used high-density polyethylene for the hollow conical dielectric. The length andinner diameter of the hollow conical dielectric were 83
and 10 mm, respectively. It was located at 0.4 m from thealuminum foil mirror upstream. An aluminum collimator,
whose length and inner diameter were 150 and 8 mm,

Shield wall
Experimental room

Murtin-Puplettinterferometer

Si bolometer

Fig. 1

Schematic layout of the CCR-MCP experi-

ment in the KURRI-LINAC.
1.0

CCR+CTR
CTR

0.8

Intensity [ a.u. ]PRINCIPLE OF CCR-MCP: The CCR intensity increases proportionally to the length of the electron trajectory in the dielectric [2]. The CCR power obtainedwith a long dielectric tube can be higher than power ofcoherent transition radiation (CTR). However, the CCR isemitted onto a conical surface whose apex locates at theelectron beam, so that it is difficult to form a plane waveof the CCR beam with matching the phase. Then, a hollow conical dielectric with its apex facing the incident
electron beam was proposed to overcome this difficulty[1]. By setting an angle between the generatrix and rotation axis to be half of the Cherenkov angle, all CCR thatis reflected by the conical surface is in phase, forming
CCR-MCP on the base of the hollow conical dielectric.
When the absorption coefficient and the refractive index
of the dielectric are expressed as  and n, respectively,
the CCR-MCP beam saturates at a certain length LC,
which is given byn 1  n ,
LC 
ln

n
where  is the ratio of the electron speed to the speed oflight. Because it is easy to focus a plane wave, more
powerful THz light can be obtained by using a hollow
conical dielectric with very low absorption coefficient.

Vacuum chamber

Accelerator room

0.6

0.4

0.2

0.0
0

5

10

15

20

25

30

Wavenumber [cm-1]

Fig. 2

Spectra of the CCR with the CTR.

was installed in front of the hollow conical dielectric not
to expose the hollow conical dielectric to the electron
beam. The electron energy was 42 MeV, and the charge ina micropulse was approximately 40 pC.
RESULTS:The CCR-MCP beam was observed with
CTR beam generated at the aluminum foil mirror by aMartin-Puplett type interferometer. When the hollow
conical dielectric was turned in the opposite direction,
only the CTR beam was observed. Figure 2 shows themeasured spectra of the CCR-MCP and CTR beams. The
CCR-MCP intensity was strong three times of the CTR
intensity. Our experimental results suggest that one canproduce an intense THz light source based on the
CCR-MCP with using more compact and high-charge
electron beams.
REFERENCES:[1] N. Sei et al., Phys. Lett. 379 (2015) 2399.
[2] T. Takahashi et al., Phys. Rev. E 62 (2000) 8606.

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CO12-2

Effective Measures on Safety, Security, Hygiene andDisaster Prevention in Laboratories

T. Iimoto, R. Hayashi, S. Higaki, N. Kutsuna, A. Ko-bashi,
K. Tanoi, K. Kamiko, K. Nakahira, Y. Yuki, S. Fukui, K.
Kimura, Y. Seki, A. Shuhara, J. Nunokawa, Y. Obara, K.
Maedera, T. Takahashi1 and S. Takahashi1
The University of Tokyo
1
Research Reactor Institute, Kyoto University
INTRODUCTION:
Important research aspects can be found in the following
keywords such as safety, security, hygiene and disasterprevention. Nuclear research reactor is one of representative facilities together with these keywords under theiroperation. It is effective to investigate the latest status onpractical measures on these keywords in various facilities
including nuclear research reactors, to compare each other among facilities, and to discuss more optimized ones
for our positive safety management. Through this process,it is also essential to investigate the latest international
and/or national regulations and the movement of revisionof them. This total discussion contents and its fruit are
directly useful for all relating laboratories.
RESEARCH APPROACH:
General research approach is as follows.
- Measures of safety management during operation or
standstill status of the real facilities would be investigated. This information would be used for our research
discussion on the positive and more optimized safety
management.
- It would not be a single year research, but maybe two to
three years research for one theme.
- Information source of facilities would not be only KUR,
KUCA or the other facilities in Kyoto University, butalso the Kinki university research nuclear reactor or thefacility of National Institute of Fusion Science, etc. This
research is an active joint-research with these relating
facilities and positive researchers on safety management.
- One of the distinctive features of this research is to involve office staffs as cooperators as well as researchers
and technical staffs. In The University of Tokyo, most of
the members in Division for Environment, Health and
Safety are office staffs who knows real situation ofsafety management in laboratories very well.
Discussion target in FY of 2015 was determined as“safety control in use of small amount nuclear materials”
through our member discussion. When using small
amount of uranium (U) or thorium (Th) up to 300g (U)and/or 900g (Th), most of safety control procedures requested as radioactive materials are exempted by related
regulations. We investigated the real situation of usage

and safety control of small amount of U and Th in Japanese laboratories. In addition, training and education tosafety managers, users and officers relating small amountof U and Th were also discussed.
LATEST SITUATION ON USE & SAFETY CONTROL OF SMALL AMOUNT of U & Th:
The following information was obtained by means ofquestionnaires which were sent to 37 users of small
amount of U and Th in Japan.
Usage
Among 33 users who answered the questionnaires, it was
24 users to really use U and/or Th. 9 users do not use andjust storage the materials in their laboratories. 17 users
answered that they used the materials for the dyeing of
the bio-sample in the electron microscope observation.
Safety Control
16 users among 24 handled the small amount of the materials in general areas without setting specified areas.
Radiation safety control is not requested in the Japanese
regulation for the materials, however about half of realusers take some safety measures.
Waste
18 users among 24 keep and storage their nuclear wastes
in their facilities. There were many opinions in hope ofcollection of the waste by the government to disposethem. Hesitation and confusion were seen in some users
about the consumption and the storage disposal of thenuclear materials. Information sharing on the waste
management is essential.
NEXT RESEARCH TARGETS;
We started to discuss on the education framework, curriculum and textbooks for safety managers and users aswell as relating officers to fill up the nuclear material
controlling sheet for the use of small amount of U and Th.
This discussion and establishment should be continued
next year.
We express our gratitude for their strong support and active discussion of Dr. K. Yasuda (Kyoto University), Dr.
M. Takahashi, T. Saze (National Institute of Fusion Science) and Dr. H. Yamanishi (Kinki Univesity) and others.
REFERENCES:[1] T. IIMOTO, Environ. & Safety, 4(3),1-8 (2013)[2]T. IIMOTO et.al., Safety Engineering,48(4),215-221(2009)[3] T.IIMOTO et.al., Isotope News, 566,64-67, (2001)

27016- 103 -

CO12-3

Test of a Microcell Multi-Wire Proportional Chamber for a
Muon-Electron Conversion Search Experiment, DeeMe

H. Natori, N. Abe1, M. Aoki2, Y. Furuya3, S. Mihara, D.
Nagao2, Y. Nakatsugawa, T. M. Nguyen2, H. Nishiguchi,
Y. Seiya3, T. Takahashi1,Y. Takezaki3, N. Teshima3 andK. Yamamoto3

2-staged amplifiers to compensate slow tail by ion
movement. We have manufactured the final version of
the chamber and the amplifier. This experiment wasplanned to be the first test of the final detector system
under the condition equivalent to the final DeeMe condition.

High Energy Accelerator Research Organization (KEK)
Research Reactor Institute, Kyoto University
2
Department of Physics, Osaka University
3
Department of Physics, Osaka City University
1

INTRODUCTION: Discovery of Higgs boson filled
the last piece of the Standard Model (SM) of elementary
particle physics. The next coming issue is the physics
beyond the SM (BSM). A discovery of mu-e conversion
may be a clear clue to the BSM. DeeMe is going tosearch for mu-e conversion in J-PARC. The detector isrequired to tolerate to prompt burst pulses with an instantaneous hit rate of approximately 100GHz/mm2 andwidth of 200ns and to detect electron signal with delay
time of O(μs) from the burst pulse. We have invented a
new technique of dynamic gain control of wire chamber
to avoid a long dead time by space charge effect.
EXPERIMENTS: Experimental setup is shown schematically in Fig. 1. Electron beam collimated to 18mm x
20mm penetrates a Multi-Wire Proportional Chamber(MWPC) and beam counters. Beam rate is tuned changing current of electron gun heater.
Intensity control byheater power
Accelerator

e- gunPulse electron Field emission electrons
200ns width
Flat time distribution
within 4us of RF injection

Fig 1. Experimental setup

Acrylic board& PMTsCherenkov light

MWPC

Accelerator

Collimator

ND filter
Attenuate 10-3

Plastic
scintillator& PMT

The pulsed electron beam with tuned beam rate generated
from the beam gun emulates the prompt burst pulse. Delayed electron signals are emulated by field emission
electrons.
DC high voltage (HV) is applied to anode wires.
MOSFET based switching module makes a pulsed HV to
be applied to potential wires of the MWPC. During amain pulse comes, HV is applied to potential wires tomake voltage difference between wires 0V. Soon after
the main pulse passes the MWPC, potential wires are
switched to ground level to make large voltage difference
between anode-potential wires to detect delayed electrons.
Large current is induced on the cathode strip readouts by
the rapidly changing voltage on the potential wires. Amplifier should cope with this input. Fig. 2 shows the circuit of our amplifier. We tuned the circuit elements not tomake the amplifier saturated by the large current input.
Pole zero cancelation circuit is implemented between

Fig 2. Circuit diagram of the amplifier
RESULTS: The chamber is operated with a gas mixture of Ar/C2H6. We went in a bit too much of a hurry,and exchanging the gas was not enough before applying
HV on the chamber. Discharge cut all the wires of the
final chamber. This told us importance of removing air
contamination.
We switched the purpose of the experiment to a test of
amplifiers. We replaced the broken chamber to a prototype chamber and continued the test. Amplifier test wasgood. The large current input by HV switching and burst
electron pulse did not saturate it. The baseline successfully recovered for the delayed electron.
But we encountered another problem of applying nominal
HV on the prototype chamber. A balance of electrostaticforce and restoring force by wire tension determines wire
position. The restoring force is stronger, so the wires stay
the nominal position. But the difference of the strength iscalculated to be small. High intensity electron beam may
distort the balance, and cause wire position displacementa few times per some tens of minutes. Discharge occurred
when wires get too close.
This gave us a hint of operating the chamber stable. In
this experiment, we made the voltage difference between
anode-potential wires 0V just during the burst pulse. We
take data with cycle of 25 Hz and the data-taking period
is just a few 10 micro-s. Attractive force between anode-potential wires made the wire position unstable.
Changing the scheme of applying HV can solve thisproblem. Making the voltage difference just during thedata-taking period, repulsive force works most of thetime despite of the data-taking period. This repulsive
force keeps distance between wires. Attractive force during the data-taking period is just a few 10 micro-s and theimpulse is small enough to keep the wire position stability. Based on this consideration, we developed a newscheme of switching HV after this experiment. This successfully worked to make the operation of the chamberwith nominal HV stable.

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CO12-4In-situ Analysis of Chemical Reaction between Phosphoesters and Iron Surface
by Attenuated Total Reflection Infrared Spectroscopy and Neutron Reflectometry

T. Hirayama, S. Akimoto1, M. Hino2 and N. L. Yamada3
Dept. of Mechanical Eng., Doshisha University
1
Research Reactor Institute, Kyoto University
2
Institute of Materials Structure Science, KEK

INTRODUCTION: In recent years, reduction of friction and wear in machines is one of the most important
subjects from the viewpoint of global environmental issues, energy conservation and resource saving. Especiallydevelopment of materials having excellent tribologicalproperties is required to extend the life of machine partsby reducing friction loss. Particularly, under the boundary
lubrication regime, oiliness additives and extreme pressure agents are used to reduce friction and wear. Extreme
pressure agent is commonly known to form a ‘boundary
lubrication film’ onto the metal surface via the chemical
reaction by the heat generated in the friction process. The
film prevents direct contact between metals, reducing thepossibility of occurrence of seizure. To investigate theformation process of boundary lubrication film formed byextreme pressure agent on the metal surface, attenuatedtotal reflection infrared spectroscopy (ATR-IR) and neutron reflectometry (NR) were used in this study.
EXPERIMENTS: As the sample substrate for ATR-IR,a germanium hemispherical ATR crystal which coatedthin film of iron on flat surface was used. Poly-α-olefin
and phosphate ester were used as base oil and extreme
pressure agents respectively. Eight kinds of phosphateester were selected for the study; mono-oxyl phosphateester(mono-C8(straight chain)), di-oxyl phosphate ester(di-C8(straight chain)), mono-2- ethylhexyl phosphateester(mono-C8(branch)), di-2-ethylhexyl phosphate ester(di-C8(branch)),mono-dodecyl
phosphateester(mono-C12(straight chain)), di-dodecyl phosphate ester(di-C12(straight chain)), mono-octadecacyl phosphateester(mono-C18(straight chain)), di-octadecacyl phosphate ester(di-C18(straight chain)).
First, time dependence for the reaction between phosphate ester and iron was investigated measuring thechange in peak made by the reaction between iron andphosphate ester. The IR absorbance profiles obtained for
20 hours per one hour. When the monoester of
non-mono-C18 was used, the peak was increased withtime, and the peak value was the largest in all samples(Fig. 1). NR also proved the existence of boundary film
formed by the adsorption of monoester onto the iron surface (Fig. 2(a)). On the other hand, when the diester andmono-C18 were used, the peaks did not increase withtime. NR also proved that the boundary film was notformed onto the surface (Fig. 2(b)). It means that all ofphosphoric esters were not adsorbed onto metal surface
and the adsorption characteristics depended on the molecular weight.
Second, time dependence for the reaction between phos-

phate ester and iron at high temperature was investigatedto understand the heat effect. Heating temperature was set
to be 50, 100, 150, 200, and 250ºC and heating time was
30 minutes. When the monoester was used, the peaks
from the phosphoric acids increased, and the peaks became larger than the peaks measured at room temperature.
When the diester was used, the peaks from the phosphoric acids did not increase.
From these studies, the phosphate ester with short alkyl
chains without branch easily adsorbed onto metal surface,
and their reactivity increased by heat.

Fig. 1. IR absorbance spectrum from the interface between iron and lubricant containing mono-oxyl phosphateester (mono-C8(straight chain))

27068- 105 -

Base oil only
Base oil + additive
2 hours later(a) mono-C8(straight chain)

Base oil only
Base oil + additive
2 hours later(b) di-C8(straight chain)
Fig. 2. NR profiles from the interface between iron substrate and lubricants containing phosphate ester

CO12-5 Single Event Test on On-board Computer for Nano Satellite “Horyu-4” using 252Cf
M. Cho, H. Masui, K. Taniwaki, A. Tanaka,
M. Yahia and K. Takamiya1
Laboratory of Spacecraft Interaction Engineering,
Kyushu Institute of Technology
1

Research Reactor Institute, Kyoto University

INTRODUCTION: Kyushu Institute of Technology(KIT) has been developing nano satellites as Horyu-series
since 2010. The main mission of Horyu-series is the highvoltage demonstration by solar array and the Electro
Static Discharge (ESD) experiment on orbit. Horyu-2
launched in 2012 suffered an anomaly by Single Event
Latchup (SEL) on the On-board Computer (OBC). As aresult, Horyu-2 eventually could not respond to commands from the ground station[1]. For the next satellite,“Horyu-4”, the project members recognized that a counter measure for SEL is necessary to avoid the same fateas Horyu-2. The project members decided to conduct
radiation testing using 252Cf at Kyoto University Research Reactor Institute. Radiation testing was performed
twice in 2015. We used the circuit boards of Horyu-4
including OBC, Electrical Power System (EPS) andCommunication and checked the failure modes caused by
SEL. EPS provides 3.3 V and 5.0 V lines to eachsub-system and it controls the reset system. The purposeof this test is to improve the stability of Horyu-4 underthe effects of radiation. This document reports the detailof testing and results.

to EPS. However, our measurement system could notacquire the recovering OBC because the reset signal fromthe OCP was too fast. For the second test, we improved
the measurement system. The second test was conductedin September 2015. We observed that EPS could not cut
the current feeding to OBC even though OCP properly
detected over current. As a result of the investigation, aleakage current from 5.0 V line to 3.3 V line affected thereset system when EPS cuts the current of 3.3V line to
OBC. To execute a proper reset, EPS must cut the currentof 5.0 V line, too. We improved the configuration of thereset system and confirmed the reset system.
The improved Horyu-4 system was verified by this radiation test. Horyu-4 was launched on Feb 17th 2016 andachieved its main mission as the world’s first acquisitionof ESD waveform and image on orbit[2].

EXPERIMENTS: Figure 1 shows the experimental
set-up. Circuit boards used in this test were EM and FM
models for Horyu-4. These boards have as microprocessors H8 and PIC. The plastic package of microprocessors
was removed so that the core of the microprocessors was
directly exposed to 252Cf source. The circuit boards were
set in a vacuum chamber. The pressure during the test
was approximately 30 Pa. The voltage and current fed
from the power supply were measured by a DAQ andoscilloscope and the operation of the microprocessors
was verified by a PC with RS232 communication. An
over-current protection (OCP) was implemented in the
power line between each sub-system and EPS in the circuit boards. Once OCP detects over current due to SEL
on the OBC, OCP sends a reset signal to EPS. To recoverfrom the hang-up state of OBC by SEL, EPS automatically cuts the current from EPS to OBC. In this experiment, 252Cf source was mounted on XYZ stage shown in
Fig. 2 and its position and height were controlled by astage controller. The distance from microprocessors to
the radiation source was from 10 mm to 30 mm.
RESULTS: The test procedure is as follows.
1) Check operation of the circuit board2) Move 252Cf source to above the microprocessor.
3) Monitor the system by PC.
The first test was conducted in August 2015. In the first
test, the OCP seems to be able to detect the over current
inducedby SEL on the OBC and the reset signal was sent	
 Fig. 1 Test Setup

Fig. 2 252Cf source mounted on XYZ stage
REFERENCES:[1] M. Cho et al., The Japan Society for Aeronautical andSpace Sciences, 12 17-24 (2013).
[2] T. Shimizu et al., Proceeding of Spacecraft Charging
Technology Conference, (2016)

27069- 106 -

CO12-6

Ethnographic Study on Nuclear Reactor- Radiation Hazard and Risk Management for Evacuee’s Future in Fukushiama -M. Takagaki1, K. Uno1, S. Masunaga2
1
2

Leuis Pasteur Center of Medical Research
Research Reactor Institute, Kyoto University

In order to know about nuclear reactor in layman term, it
might be highly helpful to describe it as ethnography byinvestigating how it has been concerned in human civilization. In this report we describe ethnography of evacuees from Fukushima Nuclear Accident in order to recoverand live together in low dose radiation field as a different
culture, in other words to know about it’s various aspects
and complicated conditions in constructing their new
culture.
Topics of this progress report: We investigated the complicated difference between physical dose of radiation
exposure (hazard) and sensibility feeling (risk) throughscientific field works in Fukushima. And we discuss
about the possibility to live in evacuee’s hometown contaminated with low dose radiation (mainly 137Cs).

It is essentially very difficult to apply anthropologicalstudy in Fukushima from an ethical standpoint. Fortunately, we overcome this difficulty by applying scientific participation in refuges to keep good relationshipwith refugees. Figure 1 shows radiation dose of anevacuee who lives in refuge and regularly visit his
home in contaminated area with low dose radiation.
His average radiation dose is 1.97µSv/day in his refuge, but it rises to 6.70µSv/day during stay in his
home.

Figure 1. Daily fluctuation of radiation dose determined by apersonal dosimeter (miniDOSE, Ray Systems Co.) H: at home,
R: at refuge.

He says, “It’s more healthy to work in my contaminated yard than being in refuge for my safety”. Fortunately he has regulated his radiation dose to be underregulated limit, <1mSv/year, by managing the periodof home-stay and also the amount of edible wild plants
cropped in his contaminated mountain. Figure 2 shows
the radiation surface dose (1m high from the ground),the dose vary with altitude and configuration.

Figure 2. The radiation dose distribution in the mountain yard.
HOME:aroung 0.3 μ Sv/hr, RELATIVE HOT area in themountain yard: 0.9-1.3μSv/hr. Date from Fukushima Project,measured by Hot Spot Finder, HSF-1, Nihon Shahei Giken, Co.

He says. “I will eat the delicacies of the seasons up in
mountain because I will miss it behind the season.” He
can calculate a limited intake amount of delicacies tobe under safety level. This case shows that possibilityof living in contaminated hometown by analyzing thehazard and accepting the risk.
On the very beginning of Fukushima Nuclear Accident,
why scientist’s statements about radiation hazard & risk
were so different among them? There is no doubt that we
scientists are responsible to such situation. Our next concerns about Fukushima in this research are scientific participation and inspection on the actor network among
nuclear scientists.
REFERENES(1) Leave politics out of science. Editorial Review Nature
Medicine 22, 447 (2016)(2)Fukushima Nuclear Accident Report of Japanese Ministry,
http://tenkai.jaea.go.jp/sanko/hokokusyo-jp.html(3)M. Takagaki. Ethnographic Study on Nuclear Reactor. presented on 50th JASCA Congress on 05.28-29, 2016, Nagoya

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CO12-7

The XEP-e (eXtremely high Energy Plasma/ particle sensor for electron)of the ERG Satellite

N. Higashio, T. Takahashi1 and N. Abe1
Table. 2.Parformance of the XEP-e
Japan Aerospace Exploration Agency
1
Research Reactor Institute, Kyoto University

INTRODUCTION: The radiation belt called the Van
Allen radiation belt exsists within the geospace that is theregion of outer space near the Earth. It often causes asatellite’s trouble. The Exploration of energization andRadiation in Geospace satellite (ERG) that is the
JAXA’s project will be lanched from the Uchinoura
Space Center in 2016FY. This project aims at elucidating
how highly charge electrons have been born while theygenerate and vanish repeatedlly along with space storms
caused by disturbance solar wind. This satellite has four
instrument parts, a Plasma Particle Experiment Suite(PPE), a Magnetic Field Experiment (MGF), Plasma
Wave Experiment (PWE) to measure radiation particles,
magnetic and electronic waves. The eXtermely high Energy Plasma/particle sensor for electron (XEP-e) is one of
the PPE. It aims at measuring electrons from 400keV to
20MeV. We are now developing its Flight Model andused the KURRI-LINAC (Kyoto University) to calibrate
it over 2 MeV electrons.

We used the KURRI-LINAC (Kyoto University) to calibrate its energy that is between 2MeV and 20MeV electron. We also used our accelerator in Tsukuba space center under 2MeV electrons. We need very low count rate
beam like 100~1000cps, we have already got datas tomake a beam by using the XEP-e (Engineer Model) lastyear. In this year we calibrated the XEP-e (Flight Model).
As shown in Fig. 2, datas of the the KURRI-LINAC andsimulation datas (GEANT4) were very similar between
6MeV and 20MeV. It shows that the KURRI-LINAC canmake very low count rate beam.

Table. 1. Mission Profile of the ERG
ERG satellite
Lunch
Configuration
Orbit

Date
Location
WeightAltitude

2016FY
Uchinoura Space Center
350kg
Perigee:about 300km
Apogee:about 30,000km

Inclination
Type of
Orbit
Period31°
Elliptical orbit

Fig. 2.

about 538 min

EXPERIMENTS: The XEP-e’s profile shows Table. 2.
It has five solid-state silicon detectors (SSDs) and ahigh-Z scintillator (GSO). The XEP-e is Fig.1. The first
SSD discriminates between electron and other particles.
And The Other SSDs and a high-Z scintillator decideenergy of perticles that are detected.

Incident energy vs Loss energy channels of the
XEP-e(energy range: 6MeV~20MeV)RESULTS:The XEP-e could caliblate by using the KURRI- LINAC (Kyoto University) that is only a facility in Japan thatmakes low count rate electrons beam between 5MeV and
20MeV.

Fig. 1. XEP-e(Flight Model)

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