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  • “Soft error test service” commences to reproduce “soft errors” - abnormal operation of electronic equipment caused by cosmic rays

NTT Press Releases

(Press release)

December 19, 2016

Nippon Telegraph and Telephone Corporation
Nagoya University
Hokkaido University
S.H.I. Examination & Inspection, Ltd.
NTT Advanced Technology Corporation

“Soft error test service” commences to reproduce “soft errors” - abnormal operation of electronic equipment caused by cosmic rays
- Compact accelerator-driven neutron irradiation service is commercialized to contribute to even greater reliability of advanced electronic equipment -

Nippon Telegraph and Telephone Corporation (Headquartered in Chiyoda-ku, Tokyo, CEO Hiroo Unoura, NTT hereinafter), in partnership with Nagoya University (Nagoya city, Aichi Prefecture, President Seiichi Matsuo) and S.H.I. Examination & Inspection, Ltd. (Headquartered in Saijo City, Ehime Prefecture, CEO Masahiro Akiyama, SHIEI hereinafter), have verified the applicability of compact accelerator-driven neutron source*2 available to general companies for reproducing faults of electronic equipment caused by cosmic rays (soft errors)*1, and have established a test method to reproduce soft errors.
In addition, NTT Advanced Technology Corporation (Headquartered in Kawasaki City, Kanagawa Prefecture, CEO Joji Kimura, NTT-AT hereinafter) will start a soft error test service using a compact accelerator-driven neutron source on December 19, 2016.
As telecommunications equipment becomes more compact and energy saving with higher functionality and performance, this service promises improvements to equipment reliability by offering prediction of abnormalities due to soft errors in the development and testing stage, as well as confirmation of error detection and remediation systems designed to cope with soft errors.
There are also plans to expand the scope of this application to various other electronic equipment requiring high levels of reliability.

Figure 1 Soft error generation mechanismFigure 1 Soft error generation mechanism


In recent years, there have been strong demands for electronic equipment that is compact, energy saving, highly functional and high performance, which means semiconductor devices require high levels of integration. Meanwhile, the earth is constantly being showered with neutrons that occur as a result of cosmic rays colliding with the atmosphere.
As semiconductor devices become more integrated and miniaturized, the electric charges required to determine bits in devices have become smaller and smaller. For this reason, these devices are easily affected by tiny charges of the secondary-particles in neutrons resulting from cosmic rays, which means that compared to older electronic equipment, the rate of soft errors is on the rise (Figure 1).
To improve reliability of telecommunication equipment, NTT has conducted research into soft errors caused by neutrons. In 2013, it was assumed that soft errors could be caused using a compact accelerator-driven neutron source. Hence, soft error testing technology was jointly established at Hokkaido University’s (Hokkaido, Sapporo city, President Keizo Yamaguchi) compact accelerator-driven neutron source*3 *4.
Also, as telecommunication equipment soft errors gain an increasing amount of attention around the world, NTT Network Service Systems Laboratories has led standardization activities in the International Telecommunication Union, Telecommunication Standardization Sector (ITU-T). ITU-T K.124 “Overview of particle radiation effects on telecommunications systems” was approved as a Recommendation at the ITU-T SG5*5 meeting held in October 2016

From these beginnings, towards commercializing a soft error testing service, NTT has continued joint research with SHIEI and Nagoya University to confirm that soft error testing is possible with a compact accelerator-driven neutron source owned by a general company, the results of which have enabled NTT-AT to begin providing a soft error testing service.

2.The joint experiment results

Using the SHIEI-owned compact accelerator-driven neutron source*6, joint experiments were performed to (1) reproduce soft errors, (2) greatly reduce the time to reproduce soft errors, and (3) build a system to control the area irradiated with neutrons (Figure 2). In this experimental system, neutrons with an energy level that enables soft error testing were produced by irradiating a beryllium target in a cyclotron with protons accelerated to 18MeV.
Prior to the experiment, a particle transport simulation was performed to determine the spatial distribution of the neutrons.

(1)Soft error reproduction

We confirmed that soft errors could be reproduced using the SHIEI-owned compact accelerator-driven neutron source.

(2)Significant reduction in soft error reproduction time

By testing in the vicinity of the neutron generation source in this accelerator, the time taken to reproduce soft errors was reduced to 1/100 of the older method. This is equivalent to about 100 million times that of the natural world. We also confirmed that this ratio can be freely adjusted.

(3)Controlling the neutron irradiation area

In this experiment, we confirmed that the irradiation area can be controlled to handle irradiation of particular LSI devices within a system, or irradiation of entire systems. Specifically, we confirmed that testing is possible with irradiation of only a specific area of a few square centimeters or a wide area of about 50 × 50 cm.

Figure 2 Soft error testing system with the SHIEI-owned compact accelerator-driven neutron sourceFigure 2 Soft error testing system with the SHIEI-owned compact accelerator-driven neutron source

click image to enlarge  

3.Soft error test service

NTT-AT will offer a test service that entails irradiating equipment under test with neutrons to detect errors that occur and hence measure the equipment’s resilience against soft errors in the real world.

(1)Test method and detection criteria

This complies with international standards under development in ITU-T SG5.
It is possible to estimate the probability of soft errors occurring in the field from results of testing done at the component or equipment level. Also, it’s possible to check the operation of equipment in which soft errors have occurred (Figure 3).


- There are cases of telecommunication equipment providing network services malfunctioning temporarily, although the cause of those malfunctions cannot be determined even through failure analysis done by the equipment manufacturer. In such cases, it is possible to determine whether a failure was due to a soft error by using this service to reproduce soft errors. The service also makes it possible to check the effectiveness of soft error countermeasures put in place with the equipment.
- Through the early discovery of locations in which soft errors can occur, the service also enables countermeasure implementation in advance at the equipment design stage.

(3)Service start date

December 19, 2016

(4)Service fees and application method

Please make all inquiries to the contact below.
NTT Advanced Technology Corporation, Advanced Products Division, Environment Business Unit, EMC Center
TEL: +81 (0)422-51-9811 Email:
Soft error testing service application page: (Japanese)

To use this service, a quotation will be provided to customers on prior consultation about the details of testing, and then testing will be done on the equipment at the compact accelerator-driven neutron source facility at SHIEI etc. After that, a report of test results will be provided. (Figure 4)

Figure 3 Testing to reproduce faults occurring after network service deploymentFigure 3 Testing to reproduce faults occurring after network service deployment

Figure 4 Flow of using the soft error test serviceFigure 4 Flow of using the soft error test service


*1Soft error
Differing from “hard errors” that cause devices to malfunction permanently, soft errors are temporary errors that are resolved by restarting devices and overwriting data. The main causes of soft errors are α rays generated from trace amounts of radioactive isotopes in semiconductor devices, and neutrons generated by cosmic rays. Neutrons is caused by high-energy particles, mainly protons, emitted from the sun or supernova explosions entering the Earth’s atmosphere and striking the atomic nuclei of nitrogen and oxygen in the air, which causes neutrons in the atomic nuclei to fly off. Even if they strike a semiconductor device, most of these atmospherically-occurring neutrons pass right through without any effects, although very occasionally they react with the atomic nuclei of the silicon that makes up the semiconductor device, which causes various charged particles such as protons or α particles to be released. This results in electrical noise, which can cause temporary soft errors. As soft errors increase with development of semiconductor devices with high levels of integration and increased miniaturization, soft error countermeasures are becoming a more urgent concern.
*2Compact accelerator-driven neutron source
A comparatively small accelerated neutron source of several meters in size. Historically, mainly in the fields of physics, materials and biology, large-size nuclear reactors or accelerators several hundred meters in length have been used to generate neutrons. Such large facilities only exist in a few places in Japan, and their availability is limited. In contrast, compact accelerator-driven neutron sources of only a few meters in size can be set up in a wide range of localities, even in urban facilities. Hence, expectations for compact accelerator-driven neutron sources are on the rise, and they are rapidly being constructed in various places around the world.
*3Hokkaido University’s compact accelerator-driven neutron source
Completed in 1973, this is the 45MeV electron linear accelerator facility constructed by School of Engineering, Hokkaido University. Being a comparatively small experimental facility that offers a high degree of freedom and enables a wide variety of neutron experimentation using its accelerator, this facility has been producing results for over 40 years.
*4Technology to prevent information and telecommunication equipment trouble from cosmic rays ~Efficient soft error testing technology using a compact accelerator-driven neutron source~
ITU is an institution of the United Nations. ITU-T is concerned with standardization of tele communications.
SG5 (Study Group 5) investigates issues with the environment and climate change.
*6The SHIEI-owned compact accelerator-driven neutron source
Neutrons are produced by irradiating a beryllium target with protons accelerated using a Sumitomo Heavy Industries cyclotron (a circular accelerator called CYPRIS 370). The protons are accelerated to an energy of 18MeV. With dimensions of 2.4 m×1.8 m×2.0 m, this cyclotron is extremely compact.

For inquiries, please contact:

NTT Information Network Laboratory Group

Planning Department, Public Relations Section
TEL: +81 (0)422-59-3663

Innovative R&D by NTT
NTT Has Instituted a Logo to Represent R&D Activities.

Nagoya University

<1> Inquiries regarding this research

Nagoya University, School of Engineering/Graduate School of Engineering, Accelerator BNCT Systems Research Course
Professor, Yoshiaki Kiyanagi
TEL: +81 (0)52-789-3614

<2> Inquiries regarding the media

Nagoya University Publics Relations Office
TEL: +81 (0)52-789-2016

Hokkaido University

<1> Inquiries regarding this research

Hokkaido University, Factory of Engineering, Division of Quantum Science and Engineering
Professor Michihiro Furusaka
TEL: +81 (0)11-706-6677

Assistant Professor Hirotaka Sato
TEL: +81 (0)11-706-6679

<2> Inquiries regarding the media

Hokkaido University, General Affairs and Planning Department, Promotion Department, External Affairs Section
TEL: +81 (0)11-706-2610

S.H.I. Examination & Inspection, Ltd.

Planning and management department
TEL: +81 (0)898-65-4868

NTT Advanced Technology Corporation

Corporate Planning Department, Corporate Communication Section
TEL: +81 (0)44-280-8823

Information is current as of the date of issue of the individual press release.
Please be advised that information may be outdated after that point.

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