冷中性子ディスクチョッパー型分光器

AMATERAS

J-PARC センター 物質生命科学ディビジョン: 中島健次、河村聖子、菊地龍弥、稲村泰弘、川北至信、梶本亮一、中村充孝、曽山和彦、田中浩道、岩橋孝明、神原理、山内康弘、青山和弘、新井正敏
A Cold-Neutron Disk-Chopper Spectrometer AMATERAS

Materials & Life Science Division, J-PARC Center: K. Nakajima, S. Ohira-Kawamura, T. Kikuchi, Y. Inamura, Y. Kawakita, R. Kajimoto,
M. Nakamura, K. Soyama, H. Tanaka, T. Iwahashi, W. Kambara, Y. Yamauchi, K. Aoyama, and M. Arai1

AMATERAS Over View

AMATERAS: By combination of high-peak intensity from a H2-coupled moderator & newly
developed fast disk-choppers for pulse shaping and monochromating, AMATERAS realizes bothhigh-resolution (∆E/ Ei > 1%@ Ei = 20 meV) and high-intensity.
Commissioning: from May, 2009
Fast Disk-Chopper
Max. Rev=350Hz
User program: from Dec. '09
Minimum Burst Time
Items which have been already installed.
Scattering Chamber, Shieldings, Chopper Systems,Beam Transport
4K Refrigerator: Bottom Loading Type
Main Detectors
266 tubes installed (60% of full installation).
Covering Angle：Horizontal 4.7˚～111.7˚
Vertical -16˚～22˚
2 Beam Harrowers
Oscillating Radial CollimatorCranetch_min=7.5sec.

Detectors:
3He 1D-PSD
=1 inch, L=3m
p=10 atm
Scattering Chamber
Volume: V=59m3
Vacuum Level: P<10-6 Torr

Items which have not yet installed.
Main Detectors (Remaining 182 Tubes)
Slow Disk-Chopper
Beam Monitors
Rev=12.5&25Hz
Polarization Options
Open Angle 0º~175º
etc.
(Variable)

Energy Resolution
010

Fat Dsik-Chopper #2 30mm slit
pulse shaping off

Fast Disk-Chopper #2 10mm slit
pulse shaping off-110-20.1-0.02

1010000.02

0.04

0.06
0.04
0.02

00.01 0.02 0.03 0.040.025

Ei=1.05meVIntensity (arb. unit)

In actual experiments, most of users prefer low speed
operation of chopper (f=150Hz) with the resolution of afew hundred μeV ~ a few meV.

Ei=1.69meVE/Ei=0.0088meVEnergy(meV)

Incident Energy (meV)

By using the pulse shaping chopper, we can obtain theenergy resolution of less than 10 eV at lower Eis.

0.08

0-0.04 -0.03 -0.02 -0.01-310.2

0.1

Fast Disk-Chopper #2 10mm slit
pulse shaping on
100.3-0.040.02

Fast Disk-Chopper #1

Fast Disk-Chopper #2

High Peak Intensity
Fine Pulse Shape
Tunable Width
Ideal Source

cf. CNCS@SNS, LET@ISIS TS-2

E/Ei=0.0058meV

Effort to Expand Possible Dynamic Range

Previously： We can choose only 1 frame width → narrow range

Power of multiple-Ei measurement
Zoom-in & zoom-out operation by using asingle measurement data.
Taking Different resolution (time-scale)data by a single measurement
Dynamics contains different time-scales (liquids,polymers, biomaterials...) can be measured
effectively and precisely.

LFrom1) M. Russina and F. Mezei, Nucl. Instrum. Methods Phys. Res. A604 (2009) 6242) M. Nakamura et al., J. Phys. Soc. Jpn. 78 (2009) 093002

Ei=90~3.8meV

LToDetector

Detector

Sample
FDC#2Sample
FDC#2

FDC#3
SDC#2
SDC#1
FDC#1

FDC#3
SDC#2
SDC#1
FDC#1

TT

40msec.

40msec.

L

When we use FDC#1, we have large
band width (=1.9Հ@300Hz
operation of FCD#1) So, we can takeanother Ei between 2 Eis.

Detector
Sample
FDC#2

FDC#3
SDC#2
SDC#1
FDC#1

T40msec.

42.1meV

We can take 42.4meV, 7.8meV,3.1meV, 1.7meV without overlapping
up to the energy transfer of 0.53Ei.

7.74meV

3.13meV

AMATERAS is potentially able to performmeasurements in the range of 10eV ～several 10meV (nearly 5 orders).

0.01
0.005
0-0.04

-0.02

00.02

0.04

Energy(meV)

Statistics of AMATERASUser Program in JFY 2013

2013A
・General Use Proposals: Accepted 9 (61 days), Reserved 4 (23 days) (# of submitted prop.: 22)
・Project Use Proposals: 2 (25 days)
・Elementary Strategic Use: 1 (3 days)* Due to the accident at Hadoron Fac., user program for JFY 2013 was quited in the end of May.
4.5 general proposals and 1.5 project use proposal has been carried out.
2013B・General Use Proposals: Accepted 4 (22 days), Reserved 2 (10 days ) (# of submitted prop.: 18)
・Elementary Strategic Use: 1 (3 days)

Commissionig in JFY 2013

Fixing of Beam Transport
Low Neutron Flux at the Sample Position

The neutron flux at the sample position is turned out to be 1/10of that of expected value.

Commissioning started from: May 2009
User program started from: December 2009

Number of proposals carried out:
・General Use Proposals: 43
・Urgent Proposals: 1
・Project Use Proposals: 6 (or 15 prop.-term.)
Beam time provided to user program:・ General Use Proposals: 210 days
・ Urgent Proposals: 4 days
・ Project Use Proposals: 95 days
Publications(except technical (instrumental) out-comes)
・Papers: 13 (published & accepted)
・Presentations in scientific meetings: more than 60

・Fixing of beam transport section
・Commissioning on SE
・Replacement of a gas-leaked detector
・Preparation of beam monitors & attenuators
・Background reduction
・etc.

Proposals for 2014A
・ General Use Proposals: 22
・ Project Use Proposals: 2・ Instrumental Proposal: 1
Flux at Sample Position

Simulation
1/10 !!
of simulation result

Observed

Miss-alignment in the curved section is found.
Part of mirror show bad reflectivity.

Replacement (8.6m) and re-alignment (full-section) of guide mirror have been carried out.
AMATERAS will have ×10 higher intensity from the next round???

Ei=3.7~1.0meV

New Choice：More than 1 frame width

0.015

Activities in JFY 2013

At the exit of biological shield (before the curved section),the measured flux is OK. Therefore, the source of problem
is in the curved section or later of that.

+Coupled
Moderator

Multiple-Ei measurement utilizing repetition
rate multiplication1） was demonstrated on
4SEASONS2） and is becoming an ordinal(usual) measuring mode of chopper
spectrometers at MLF.

Ei=3.14meV
E/Ei=0.022meV

Energy(meV)

calculation
100.40Intensity (arb. unit)E (meV)

Intensity (arb. unit)

CH02 300Hz 30mm or 10mm slit
CH01 open (pulse shaping off)
300Hz (pulse shaping on)

By using pulse shaping chopper, wecan cut put the peak of the pulse fromhigh intensity coupled moderator.
Enjoy high peak intensity without
degrading of the resolution.
By tuning shaping width, we canoptimize the intensity and theresolution.

High Intensity
Bad Pulse ShapeMultiple-Ei Measurements

0.5

110

Super Mirror Beam Transport
3Qc&3.8Qc Super Mirror
Horizontal Geometry: Curved Guide (R=2Km)
Vertical Geometry: Straight + Elliptic

Pulse Shaping & Couple Moderator

Replace with new mirror

Re-alignment

1.68meV