実験報告書様式（装置グループ利用）
提出日 Date of report

MLF Experimental Report

2014/10/9

実験装置名／ＢＬ番号 Name of Instrument/BL
ANNRI/BL04
実験装置責任者 Name of the person responsible for the instrument:
原田秀郎 Harada Hideo
所属 Affiliation: 日本原子力研究開発機構 Japan Atomic Energy Agency

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 goup, (b) significant user support works, and (c) statistical summary of userexperiments.
(a)・Feasibility study for prompt gamma-ray analysis
We have conducted to investigate the methodology and feasibility of developing a new prompt gamma-rayanalysis. Standard samples were measured using two Cluster Ge detectors from the viewpoint of prompt
gamma-ray activation analysis. We have measured the background, and obtained PGA, TOF, TOF-PGA, MPGA,TOF-MPGA spectra.
・X-stage Collimator
We have added a removable collimator at flight length of
13.5m (Figure 1). The collimator is called “X-stage collimator”.
Using the “X-stage collimator” and the other removable
collimator, “Rotary collimator”, users can select the beam sizeof 22mm, 7mm, well collimated 6.5mm, and pencil formed
15mm. In this set-up, the neutron flux for 6.5mm is aone-sixth strength comparison to that for 7mm and that for
15mm is a one-twentieth strength.
Fig.1 Installed new removable collimator

・LiF ShieldIn the ANNRI, borated-rubber sheets were used for neutron shield for the Ge spectrometer. Indeed, 10B(n,)reaction have large neutron capture cross-section and 10B is suitable for the material for neutron shield. However,strong 478-keV  rays are emitted from the 10B(n,) reactions. The  rays make huge background. On the otherhand, 6Li(n,) reaction also has large neutron capture cross-section and weak  rays are emitted from thereaction. Therefore, we have replaced the borated-rubber sheets by 6LiF tiles.
Figure 2 shows normalized capture yield for 118Sn with the borated-rubber sheets and the 6LiF tile. Using the6

LiF tile instead of the borated-rubber sheets, the background due to 10B(n,) reactions are drastically reduced.
1１．研究成果概要（つづき） Outline of experimental results (continued).

Fig. 2 Normalized capture yield for 118Sn with the borated-rubber sheets and with the 6LiF tile.
・NaI DAQ
Conventional systems for the NaI(Tl) detector in ANNRI, consisting of an analog shaping amplifier and apeak-hold analog-to-digital converter, cannot processes a high counting rate of events without a large counting
loss. Therefore, a fast data acquisition method based on pulse width analysis was developed for -ray
spectroscopy with an NaI(Tl) detector. The new method was tested in experiments with standard -ray sources
and a pulsed neutron beam from a spallation neutron source. Pulse height spectra were successfully reconstructedfrom pulse width distribution by use of an energy calibration curve.
(b)
The provision of advice, suggestions and useful information for sample preparation (size, weight, packing
material etc.), the experimental setup (DSP mode, size of the collimators, measuring time etc.) and the spectra(TOF, PGA). Instructions for the sample changer.

2１．研究成果概要（つづき） Outline of experimental results (continued).

(c)・2012A
4 days (elemental analysis)
7 days (whole beam line : performance test)
4 days (nuclear data : neutron energy distribution)
5 days (nuclear astrophysics : DAQ of NaI detectors)
11 days (nuclear data : DAQ of Ge detector)
・2012B
2 days (elemental analysis)
4 days (nuclear data : neutron energy distribution)
9 days (nuclear astrophysics : DAQ of NaI detectors)
10 days (nuclear data : DAQ of Ge detector)

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.
3