実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF	 Experimental Report

提出日 Date of Report
2012 August 3

課題番号 Project No.

装置責任者 Name of responsible person

2012A0034

Norifumi Yamada

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Study of Diffuse Reflection for the Characterization of Candidate

BL16

Materials of Ultracold Neutron Storage Cell

実施日 Date of Experiment

実験責任者名 Name of principal investigator2012 June 12

Tamaki Yoshioka
所属 Affiliation
Kyushu University
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
Diamond-Like Carbon (C, D)

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

We	 measure	 the	 fraction	 of	 the	 diffuse	 reflection	 by	 observing	 the	 neutrons	 detected	 out	 of	 the	 specular	 region	 on	 the	 detector	 plane.	 One-dimensional	 distribution	 on	 the	 detector	 plane	 will	 be	 observed	 as	 a	 function	 of	 the	 neutron	 time-of-flight.	 We	 will	 convert	 the	 projected	 
one-dimensional	  distribution	  into	  the	  neutron	  rest	  frame	  so	  that	  we	  obtain	  the	  angular	 distribution	 of	 the	 vertically	 incident	 UCNs.	 We	 are	 interested	 in	 the	 UCN	 reflection	 in	 the	 velocity	 range	 of	 0-3	 m/s,	 with	 the	 velocity	 step	 of	 1	 m/s	 or	 smaller,	 which	 corresponds	 to	 the	 angular	 resolution	 of	 1	 mrad	 or	 smaller	 for	 the	 incident	 velocity	 of	 1000	 m/s.	 We	 are	 going	 to	 adjust	 the	 beam	 divergence	 1	 mrad	 or	 smaller	 so	 that	 we	 clearly	 identify	 the	 specularly	 
reflected	 neutrons.	 	 
We	 took	 data	 for	 16	 samples	 of	 diamond-like	 carbon	 thin	 film	 coated	 on	 the	 silicon	 wafer.	 We	 
made	 the	 diamond-like	 carbon	 samples	 using	 our	 coating	 machine	 by	 changing	 various	 parameters	 such	 as	 bias	 voltage.	 In	 order	 to	 understand	 our	 diamond-like	 carbon,	 we	 firstly	 evaluated	 the	 1
Fermi	 	 2. 実験方法及び結果（つづき） Experimental method and results (continued)
Fermi	 potential	 which	 is	 also	 very	 important	 parameter	 of	 a	 neutron	 mirror.	 Figure	 1	 shows	 the	 typical	 reflectivity	 data	 of	 our	 diamond-like	 carbon.	 In	 the	 previous	 experiment	 performed	 at	 
BL16,	 we	 found	 that	 there	 is	 about	 30neV	 discrepancy	 between	 measured	 and	 calculated	 Fermi	 
potential.	 We	 therefore	 took	 more	 data	 for	 Fermi	 potential	 of	 diamond-like	 carbon	 with	 another	 coated	 parameter.	 We	 also	 re-consider	 our	 formula	 for	 the	 Fermi	 potential	 calculation.	 The	 
results	 are	 shown	 in	 Figure	 1.	 We	 tried	 two	 different	 formula	 for	 the	 Femi	 potential	 calculation.	 
The	 discrepancy	 is	 still	 exist.	 	 
For	 the	 diffuse	 reflection	 study,	 we	 have	 to	 develop	 the	 de-convolution	 method	 in	 order	 to	 discriminate	 specular	 reflection	 to	 non-specular	 reflection.	 We	 are	 still	 developing	 such	 method	 

実験値ｖｓ計算値のズレ!

and	 study	 is	 no	 under	 way.	 

・"#、$##の再現性？!
両方の計算式でのズレ!
Figure 1: Comparison between measured (y-axis) and ・#%&の再現性？!
calculated (x-axis) Fermi（一様に計算値のほうが低い）!
potential. We have employed two different formula ї断面積？!
for the Fermi potential
calculation. There are 20~30 neV discrepancy in each case. The reason is not clear
and study is now under way.

2'!