[Neutron] J-PARC Newsletter No. 81
shibata.kaoru
shibata.kaoru at jaea.go.jp
Tue Feb 2 02:08:58 CET 2021
=====================================================================
J-PARC Project Newsletter No.81, January 2021
Japan Proton Accelerator Research Complex under operation jointly by the High Energy Accelerator Research Organization (KEK) and the Japan Atomic Energy Agency (JAEA) http://j-parc.jp/index-e.html
=====================================================================
HEADLINES AND CONTENTS
1. [Overview]
NEW DECADAL PLAN IN EFFECT; OVERCOMING COVID-19.
2. [Accelerator Division]
STABLE OPERATION OF THE ACCELERATORS FROM OCTOBER TO DECEMBER.
3. [Particle and Nuclear Physics Division]
2020 NISHINA MEMORIAL PRIZE FOR HADRON PHYSICS.
THE NATURE ARTICLE OF T2K ON CPV WAS SELECTED FOR 10 REMARKABLE DISCOVERIES FROM 2020.
STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT. (EDM) (E34)
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION. (COMET)
4. [Materials and Life Science Division]
THE REPLACEMENT OF THE MERCURY TARGET VESSEL WAS CARRIED OUT.
PROPOSALS FOR 2020B + 2021A COMBINED PERIOD WERE REVIEWED.
THRILLING BEAM RESUMPTION AT MUSE.
5. [Nuclear Transmutation Division]
LOW-POWER PROTON BEAM EXTRACTION BY THE BRIGHT CONTINUOUS LASER USING THE 3-MeV NEGATIVE-HYDROGEN LINAC IN J-PARC.
6. [Safety Division]
AN EMERGENCY DRILL WAS CONDUCTED ASSUMING RADIATION EXPOSURE ACCIDENT.
7. [Editorial Note]
---------------------------------------------------------------------------------------------------
1. [Overview] by Naohito SAITO
---------------------------------------------------------------------
NEW DECADAL PLAN IN EFFECT; OVERCOMING COVID-19
This is the first newsletter in the year 2021. While the pandemic still continues, we really hope that you and your dearest ones are in good health. As of January 7th, the national state of emergency was raised for Tokyo and neighboring three prefectures and seven more prefectures were added on the 13th. While we are now limiting non-essential travel and commuting to and from those regions, we are continuing the operation of Material and Life Science experimental Facility (MLF) and preparatory work at the Hadron Experimental Facility (HEF) with the preventive measures enforced. Current policies at J-PARC are described at http://j-parc.jp/c/en/j-parc-covid/index.html
In the last few months, we had stable user operation at both MLF and HEF. Actually, the start of the MLF operation was delayed due to the prolonged replacement work of the target vessel with careful treatment of the contaminations around the target. We apologize for any inconvenience this delay has caused for your research activities.
At the end of last month, we held a J-PARC-wide workshop on the 1 MW operation of MLF. Its morning session was devoted to the science program expected for the 1 MW operation, and the afternoon session covered the progress of accelerator and targetry including both neutron and muon beamlines. The importance of steady progress towards the 1 MW operation at MLF was reiterated, and the necessary conditions to achieve this goal were updated. As a quick summary, we think we have a good understanding of the accelerator and beamlines, and much better understanding of the targetry system is emerging, too. The discussions at the workshop will be further developed towards our next decadal plan at MLF, and will be reported at relevant users’ meetings in the near future.
For the rest of the J-PARC facility, the upgrades and implementation of new projects are officially included in the MEXT roadmap 2020 as a meaningful and urgent project. We will work together with the funding agency, MEXT and parent organizations, KEK and JAEA towards the earliest possible realization of the project. That includes upgrades of accelerator and beamlines towards high power at the Main Ring (MR), and muon g-2/EDM experiment, extension of HEF, and the second phase of the COMET experiment. Of course, we will try to secure the beam time at the MR towards the maximum length of nine months, while the beam time in 2021 will be limited to one and a half months due to replacement work of the power supply for the MR for doubling the repetition rate and more stable slow-beam extraction.
With these efforts, we think we now have a solid ground for the operation and upgrades for the next decade. While the improvement in working environment during and after the pandemic still needs to be worked out, we hope to work together with the users for more excitements in coming years! Therefore, our slogan does change for the new year;
“High power beams for new stage of our life!”
---------------------------------------------------------------------------------------------------
2. [Accelerator Division] by Michikazu KINSHO
---------------------------------------------------------------------
STABLE OPERATION OF THE ACCELERATORS FROM OCTOBER TO DECEMBER
A new operation run was started late in November after the summer shutdown. Accelerator studies at the beam current of 5 mA and 50 mA were carried out at the linac. The studies were followed at the 3 GeV Rapid Cycling Synchrotron (RCS) at the linac beam current of 50 mA for user operation. The main purposes of the studies were to startup the machine, reproduce the accelerator parameters, confirm the performance of some new components installed during the summer shutdown, and new parameter survey for lower beam loss, etc. On December 1st, beam was delivered to the Materials and Life Science Experimental Facility (MLF) at a beam power of 600 kW.
The neutron production target of the MLF was replaced during the summer shutdown. Due to the delay of target related work, beam tuning and user operation was postponed to December 1st, from the original schedule of the middle of November. The beam power for user operation was 600 kW as before the summer shutdown.
The studies were started at Main Ring synchrotron (MR) from December 10th, and the beam delivery to the Hadron experimental facility (HD) was resumed at a beam power of 20 kW on December 14th. After the fine tuning of the MR, we delivered beam at around 55 kW, which was the highest level for the HD user operation.
The user operation for the MLF and the HD ended in the morning of December 22th followed by the four days of accelerator studies before the year-end shutdown. After the shutdown, we will start linac tuning on January 7th followed by the RCS and MR tuning. The user program of the MLF and the HD will start on January 12th.
---------------------------------------------------------------------------------------------------
3. [Particle and Nuclear Physics Division] by T. TAKAHASHI and K. OZAWA
---------------------------------------------------------------------
2020 NISHINA MEMORIAL PRIZE FOR HADRON PHYSICS (T. Takahashi and K. Ozawa)
This year’s Nishina Memorial Prize was awarded to Prof. Nakazawa, who is a professor at Gifu University and the spokesperson of the J-PARC Hadron E07 experiment, for his study of double strangeness nuclei using nuclear emulsion plates. One of the main research topics at J-PARC Hadron Experimental facility is the study of Baryon-Baryon interactions with a double strangeness system. The strength of such interactions can be evaluated by measuring the binding energy of strangeness baryons to a nucleus. Prof. Nakazawa generated such bound states and measured the binding energies using nuclear emulsion plates. One of most important achievements is the observation of a bounded system of two Lambda baryons and a Helium nucleus, so called NAGARA event, which is obtained at KEK-PS. According to the analysis of this event, the Lambda-Lambda interaction was found to be weakly attractive with the energy of 0.67 MeV. Prof. Nakazawa continued his research at J-PARC and already found a double Lambda-Be nucleus. Fruitful information for the double strangeness system can be expected from analysis of existing data at J-PARC.
Workshops:
The 9th international school for strangeness nuclear physics (SNPSchool2020) was held from Dec. 2 to 5 at Tokai by a hybrid style of face-to-face and online. We had total 137 participants including 68 students from abroad. School web page:
http://lambda.phys.tohoku.ac.jp/snpsc2020/
A workshop for a system of readout and data acquisition was held on Nov. 26 and 27. The workshop aimed to discuss technologies related to the readout system. We had both online and face-to-face communications.
A total of 100 participants including 20 participants at Tokai attended. Web Page: https://openit.kek.jp/workshop/2020/dsys/main
THE NATURE ARTICLE OF T2K ON CPV WAS SELECTED FOR 10 REMARKABLE DISCOVERIES FROM 2020 （by Y. Fujii)
On December 14, 2020, Nature announced the top 10 papers amongst their publication, "10 remarkable discoveries from 2020".
The T2K paper on CP violation in the neutrino sector, titled "Constraint on the matter–antimatter symmetry-violating phase in neutrino oscillations", was selected on the top of the announcement. Please visit https://www.nature.com/articles/d41586-020-03514-8.
Proposal of T2K extension, T2K-II, to accumulate POT of 20x10^21 for 3sigma establishment of CP violation and precise measurement of mixing parameters, has been officially approved at the 30th J-PARC PAC.
On October 20, NINJA made a press release on precise measurement of neutrino reaction with their hybrid emulsion detector. Excellent spatial resolution of emulsion combined with a novel time stamp mechanism enabled to reconstruct neutrino interaction with unprecedented precision. Please visit http://www.nagoya-u.ac.jp/about-nu/public-relations/researchinfo/upload_images/20201020_iar1.pdf
The annual maintenance of the primary beamline was completed in early December for MR start up on December 10th.
On the contrary, the "Summer Maintenance" of the secondary beam line equipment has just begun from November.
It took months to drain out the huge inventory of radio-active cooling water in the equipment for maintenance.
This maintenance will be finished by early February to start neutrino beam operation from 2/25.
STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34) (by T. MIBE)
The E34 collaboration prepares for precision measurements of the muon anomalous magnetic moment and electric dipole moment.
The ground survey has been completed for the area where a new experimental building is planned. The detailed plans for the building and relocation of current facilities and utilities in the area are being developed.
The collaboration had an online collaboration meeting on December 8-11 to share the progress and plans.
Demonstration of laser ionization of muonium for the thermal energy positive muon source is in preparation. The experimental setup was configured at the KEK Tsukuba campus. It was transported to J-PARC.
Reassembly in the beamline is in progress now. The design of RF acceleration cavities is being developed. Some of these will be fabricated in the coming year. The spiral injection of the beam to the storage ring is being studied by using a low-energy electron beam aiming for demonstration of storage with a pulsed kicker. Procedure of assembly of the positron tracking detector is being developed with support from the mechanical engineering center. A high statistics production of end-to-end simulation has been completed. This much data allows the collaboration to study some higher-order effects.
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET) (by S. MIHARA)
The COMET experiment aims to search for the lepton-flavor violating muon reaction, mu-e conversion, with sensitivity better than 10^{-14} in Phase I.
Facility construction work continues; Main work in the beam line construction is to complete air sealing along the proton beam line for COMET (C-Line) with strong support by the primary proton beam line group. Preparation in the COMET primary target area also continues.
Construction of the proton beam dump and radiation shielding wall has started.
The collaboration has been intensively working toward integrating sub-detector components into a mu-e conversion search detector.
In addition to the main detector for physics composed of Cylindrical Drift Chamber (CDC) and Cylindrical Trigger Hodoscope (CTH), another system composed of the straw-tube tracker and LYSO calorimeter is in preparation. Assembly of the straw-tube tracker and LYSO calorimeter is ready to start in 2021.
The COMET collaboration plans to carry out an 8-GeV acceleration and beam extraction test in collaboration with the J-PARC accelerator group along with beam extinction factor measurement in the Hadron hall.
The test is scheduled in February and intensive preparation work is in progress.
---------------------------------------------------------------------------------------------------
4. [Materials and Life Science Division] by Toshiya OTOMO
---------------------------------------------------------------------
THE REPLACEMENT OF THE MERCURY TARGET VESSEL WAS CARRIED OUT
1) Neutron Source
The most important challenge to achieve 1-MW stable operation is to mitigate the pitting damage on the inner surface of the target vessel that is caused by intense pressure waves in mercury. The technology of micro-bubble injection into mercury is used to attenuate the intensity of pressure waves and suppress the pitting damage. So, surface inspection and damage depth measurement of the inner surface of the target vessel are very important data to decide the ramp-up plan of the proton beam power.
On October 7th, specimens were cut out successfully from the fore-front wall of the used target vessel which was operated with 600 kW. The maximum damage depth on the specimens was less than 0.5 mm, which was the promising result for the stable beam operation with greater beam power.
On October 15th, the used mercury target vessel was replaced with a new one, but the new target vessel had to be replaced again with another one due to misalignment of the coolant pipe.
There was also another maintenance work of the gas process system, which is a crucial device for the target replacement, to replace a vacuum pump, and it needed special care and longer time than expected to suppress the release of radioactive materials. Due to these additional works, the start of beam operation was delayed for one month, and finally the neutron production for users began on December 1st with the beam power of 600 kW. The beam operation continued stably and user program ended on December 22nd.
PROPOSALS FOR 2020B + 2021A COMBINED PERIOD WERE REVIEWED
2) Neutron Instruments and Science
After the summer shutdown for the planned maintenance, the last few weeks of the user run of 2020A was resumed on December 1st. Since we are still in the COVID-19 situation, users from several domestic areas are required to proceed with a countermeasure for visiting J-PARC. Users from abroad can be also possible to visit in accordance with the COVID-19 policy of Japanese government requiring the procedure of immigration and quarantine for stay.
The neutron general proposals for the combined period 2020B + 2021A were reviewed by the Neutron Science Proposal Review Committee/The Proposal Evaluation Committee on October 12nd. The total number of submitted neutron proposals was 384 for the general proposals. Finally, 200 general proposals were approved by the MLF Advisory Board on October 20th.
Fast track proposals are now encouraged for BL08, BL11 and BL21, to which BL16, BL17, BL18 and BL22 will be added from 2020B.
Two recent scientific press releases at MLF were as follows; (1) Strain-induced creation and switching of anion vacancy layers in perovskite oxynitrides, by T. Yamamoto (Tokyo Institute of Technology) and co-workers. (2) Application of Precise Neutron Focusing Mirror for Neutron Reflectometry - Latest Results and Future Prospects, by N. Yamada (J-PARC, KEK) and co-workers.
Two arrangements on the cooperation research and development in the field of neutron scattering science between ANSTO, J-PARC (KEK and JAEA) and CROSS (the registered institute for public beamlines) and ISIS, J-PARC and CROSS are now the final stage of conclusion, which follows the former arrangements between ANSTO/ISIS and J-PARC.
11th International Workshop on Sample Environment at Scattering Facilities (ISSE) hosted by J-PARC and neutron community has been postponed to September in 2021. (https://neutron.cross.or.jp/en/events/200906-10_e/ )
THRILLING BEAM RESUMPTION AT MUSE
3) Muon Science Facility (MUSE)
The summer maintenance of the MUSE facility, which was expected to go off without a hitch, turned out to be hectic due to the discovery of two vacuum leaks. First, in the middle of August, an airtight leak was found in the outdoor helium gas piping connecting the superconducting solenoid of D-line and the second helium compressor building. As a result of the investigation, it was found that a part of the flexible tubes had corroded due to salt damage and was perforated. Considering that this, in case of operation, could have developed a serious accident for the high-pressure gas facility, it was fortunate that the leak was identified during the regular maintenance work. The flexible tubes were replaced with multitudes of measures (anticorrosive paint, taping, etc.) to mitigate the salt damage. This case reminded us that salt damage is a common risk in J-PARC which has been exposed to a sea breeze for more than 10 years.
Meanwhile, due to the delay in the maintenance of the gas process system for the neutron source, the final maintenance work for the muon source was postponed to the delayed end of the shutdown period. When the proton beamline vacuum pumping system at the M1 tunnel was finally put into operation and the massive roof shielding was put back on, a leak was suspected in the vacuum line due to the anomalous pressure rise in a buffer tank connected behind the pumping system. The leak rate was intolerably high to prevent the muon target operation that relies on the buffer tank to store the exhaust air. In cooperation with the accelerator division, the proton beam operation was temporarily suspended to fix the problem and the suspected leaky pump was successfully replaced. As a result, the muon beam delivery was resumed on time together with neutrons on December 1st.
The muon general proposals for the period combined with 2020B + 2021A were reviewed by the Muon Science Proposal Review Committee on September 24th. The total number of submitted muon proposals was 73 for the general proposals. Finally, 39 general proposals were approved by the MLF Advisory Board on October 20th.
---------------------------------------------------------------------------------------------------
5. [Nuclear Transmutation Division] by Hayanori TAKEI
---------------------------------------------------------------------
LOW-POWER PROTON BEAM EXTRACTION BY THE BRIGHT CONTINUOUS LASER USING THE 3-MeV NEGATIVE-HYDROGEN LINAC IN J-PARC
In the previous issue of the J-PARC Newsletter #73, we described a laser charge exchange method (LCE) for the Transmutation Physics Experimental Facility, TEF-P. This LCE method is a meticulous low power beam extraction method from the high-power proton beam stream of the J-PARC linac. The LCE device consists of a bright laser with the wavelength of 1064 nm and laser transport system with beam position controllers. The negative proton (H-) beam from the J-PARC linac is exposed to the laser beam, which can strip one of the two electrons, so as to change H- to neutral ones (H0). The other electron of the H0 is finally stripped by a carbon foil so that the positive protons (H+) are introduced into TEF-P.
We installed the LCE device at the end of the 3-MeV linac in cooperation with the J-PARC accelerator division. To measure the power of the charge-exchanged H+ beam, an LCE experiment was conducted using the bright pulse laser beam. The results of this LCE experiment were summarized in ref. [DOI: 10.1585 / pfr.13.2406012]. Next, we conducted the LCE experiment using the bright continuous laser beam to extract the continuous H+ beam.
As a result of the experiment, a charge-exchanged H+ beam with a power of 0.57 mW was obtained. If the laser light from this LCE device collided with the H- beam (400 MeV, 250 kW) delivered from the J-PARC linac, the stripped H+ beam with a power of 0.70 W equivalent was obtained, and this value agrees well with the theoretical result. Thus, we established an elemental technology required for the TEF, i.e., the foundations of control technology for the extraction of the low-power H+ beam from the high-power H− beam at J-PARC.
This result was published in the online version of the Journal of Nuclear Science and Technology on December 14 [DOI: 10.1080/00223131.2020.1848654].
---------------------------------------------------------------------------------------------------
6. [Safety Division] by Kotaro BESSHO and Yoshihiro NAKANE
---------------------------------------------------------------------
AN EMERGENCY DRILL WAS CONDUCTED ASSUMING RADIATION EXPOSURE ACCIDENT
An emergency drill was conducted on Oct. 21 at the Hadron Experimental Facility (HD). It was assumed that the beam operation was started when two workers were left in the experimental area of HD. The drill included transportation and decontamination of the exposed workers, estimation of exposure doses, setup the command post and communicate with accidental site, report to headquarters via TV conference, and simulated press release. The training was conducted in consideration of preventing the spread of COVID-19 infection.
---------------------------------------------------------------------------------------------------
7. [Editorial Note]
---------------------------------------------------------------------
Past issues are available from the below link.
http://j-parc.jp/c/en/topics/project-newsletter/index.html
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Editorial Board:
Toshifumi TSUKAMOTO (Chair): toshifumi.tsukamoto at kek.jp
Kaoru SHIBATA: shibata.kaoru@ jaea.go.jp
Takatoshi MORISHITA: morishita.takatoshi at jaea.go.jp
Dick MISCHKE (English Editor): mischke at triumf.ca
Keiko NEMOTO (Secretary): nemoto.keiko at jaea.go.jp
++++++++++++++++End of Letter++++++++++++++++++++++++++++++++++++++++
More information about the Neutron
mailing list