実験報告書様式（装置グループ利用）

Experimental Report

提出日 Date of Report
2014/8/7

実験装置名／ＢＬ番号 Name of Instrument/BL: 4SEASONS/BL01
実験装置責任者 Name of the person responsible for the instrument: Mitsutaka Nakamura
所属 Affiliation: J-PARC Center

１．研究成果概要 （a）装置グループ内の成果、（ｂ）ユーザー課題実装時における特筆すべきサポート、（ｃ）ユーザー課題の執行状況について、まとめてください。A4 サイズ用紙使用のこと。
Outline of your activities.

Following results at your instrument should be reported in A4 size papers: (a)results of your instrument group, (b) significant user support works, and (c) statistical summary of user
experiments.
(a) Results of our instrument group
We could perform several test measurements to improve the performance of 4SEASONS although the J-PARC
shutdown due to the Hadron accident caused big changes of experimental plan. The details of test measurements
are as follows; calibration of newly installed detectors, performance test of N2 beam monitor, backgroundmeasurement, performance test of a Gd2O3 radial collimator (RC), software development using TrigNET, and soon. In this report, we will focus on our activity for the development of Gd2O3-RC.
The needs for inelastic neutron scattering experiments under the special sample environment such as strong
magnetic field and high temperature are recently increasing. However, the unwanted scatterings originating fromthese devices affect the detection of weak inelastic signals. In order to overcome this problem we have developed
two types of RC specialized for the chopper spectrometers at MLF. One is made of Gd2O3 blades for low-energy
neutrons, and the other is of Cd blades for relatively high-energy neutrons.
In case of magnetic scattering measurements, it should be important to detect the signal at around smallscattering angle region. Thus, our radial collimators had several blades along the direct beam path. However, there
was worry that the Gd2O3 blades whose substrate is made of polymer film may produce the backgrounds by theirradiation of direct incident beam. In order to evaluate these effects, we carried out the test measurements ofGd2O3-RC using 4SEASONS. The detector coverage of 4SEASONS is more appropriate for this evaluation. The
elastic spectra of vitreous silica rod (dia.=8.5mm) measured at room temperature with a Gd2O3-RC (blue) andwithout a Gd2O3-RC (green) is given in Fig.1. The sample was set into the 4K cryostat conventionally used at4SEASONS. From Fig.1(a) and (b), it is obvious that Gd2O3-RC can effectively shield the unwanted scatteringfrom the cryostat window and provide us the high quality data. Fig.1(c) shows the experimental result by theincident energy of 300meV where the shielding ability of Gd2O3 is getting worse. It is clear that Gd2O3 blades
along the direct beam path should cause the sufficient backgrounds for high-energy neutrons.

１．研究成果概要（つづき） Outline of experimental results (continued).
Following these evaluation tests, we decided to remove the Gd2O3 blades along the direct beam path. The Gd2O3–RC has been in use with the user program.

Fig.1: Q-dependences of the elastic structure factor for vitreous silica rod (d=8.5mm) with a Gd2O3-RC (blue) and without a
Gd2O3-RC (green). The sample is set into the cryostat and the measurements are performed at room temperature. Incident neutronenergy is (a) 37.0meV, (b) 80.7meV, and (c) 300meV.

(b) User support works
Instrument group staffs of 4SEASONS (R. Kajimoto (JAEA), M. Nakamura (JAEA), K. Ikeuchi (CROSS), K.
Iida (CROSS), K. Kamazawa (CROSS)) performed user support works in pairs. One technical staff from CROSS(M. Ishikado) provided technical support to the instrument group staff of 4SEASONS. In addition, many staffs
significantly contributed to the user support based on their specialty, such as software (Y. Inamura (JAEA)),
sample environment (Y. Yamauchi (JAEA)), electric work (H. Tanaka (JAEA)), and machine design (W. Kambara(JAEA), K. Aoyama (JAEA)).

(c) Statistical Summary of user experiments
Twelve proposals were accepted as a “general proposal” of BL01 in JFY2013. Unfortunately, many proposals
were canceled due to the J-PARC shutdown caused by Hadron accident in May 2013.
+ General proposal of 2013A: 9  3 Finished, 6 Canceled+ General proposal of 2013B: 3  3 FinishedIn addition, some special proposals such as “Urgent proposal”, “Trial use proposal”, “Elements Strategy
Initiative proposal” were also performed in JFY2013.
+ Urgent proposal (2013A0002(U))  Partially performed (due to the Hadron accident)+ Trial use proposal (2013B0093)  Finished+ Elements Strategy Initiative proposal (2013S0003)  Finished必要に応じて、A4 サイズの用紙に続きを記入して下さい。
Please use A4-size papers for further reporting, if necessary.