Journal of large-scale research facilities, 1, A3 (2015) http://dx.doi.org/10.17815/jlsrf-1-21

Published: 18.08.2015

MIRA: Dual wavelength band instrument

Heinz Maier-Leibnitz Zentrum
Technische Universität München

Instrument Scientists:
- Robert Georgii, Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching,

Germany, phone: +49(0) 89 289 14986, email: robert.georgii@frm2.tum.de
- Klaus Seemann, Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching,

Germany, phone: +49(0) 89 289 14668, email: klaus.seemann@frm2.tum.de

Abstract: MIRA is a dual wavelength band instrument operated by Technische Universität München
TUM, which provides neutrons over a wide range of wavelengths 3.5 Å < λ < 20 Å combining the two
beam ports of MIRA-1 and MIRA-2. The instruments setup is modular and allows for various di�erent
cold neutron experiments such as di�raction, spectroscopy or re�ectometry.

1 Introduction

The instrument can easily be moved from one port to the other without changing the sample environ-
ment. A variety of di�erent setup options can be combined allowing for a fast and �exible realisation
of neutron experiments using the options available:

• Cold neutron di�raction
• Cold neutron three axes spectroscopy for extreme environments in pressure and temperature
• Small angle neutron scattering (SANS)
• Re�ectometry
• MIEZE spin echo
• 3D-Polarimetry

Polarised neutrons are optional for all experimental setups at MIRA. Using the �nger detector, the
instrument has a very low background of less than 0.1 cps. For MIRA-2 a q-range up to 2.5 Å-1 with an
q-resolution of 0.01 Å-1 can be reached. Vertical and horizontal B-�elds up to 2.2 T and vertical B-�elds
up to 7.5 T are available. Temperatures from 50 mK to 1500 K can be applied using the standard sample
environment at MLZ.

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Journal of large-scale research facilities, 1, A3 (2015) http://dx.doi.org/10.17815/jlsrf-1-21

Figure 1: Instrument MIRA-2 in three axes mode (Copyright by W. Schürmann, TUM).

2 Typical Applications

• Dynamics of magentic excitations
• Determination of magnetic structures, especially large scale structures, i.e. helical spin density

waves or magnetic lattices
• Quasi-elastic measurements in magnetic �elds with high resolution
• Determination of structures and dynamics in extreme environments, like pressure
• Determination of layer thickness of �lms, for instance in polymer physics
• Re�ectometry from magnetic multilayers
• Polarisation analysis

3 Technical Data

3.1 MIRA-1

3.1.1 Primary beam

• Neutron guide: NL6-N
• Dimensions: 10 x 120 mm2 (width x height)
• Curvature: 84 m
• Coating: sides m = 2.0, top/bottom m = 2

3.1.2 Monochromator

• Intercalated HPGO ∆λ /λ = 2%
• Multilayer ∆λ /λ ≈ 3% (5% polarised)
• 6 Å < λ < 20 Å

3.1.3 Max. di�erential neutron �ux at sample

• 5 · 105 n cm-2s-1 at 10 Å
• 2 · 105 n cm-2s-1 polarised

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http://dx.doi.org/10.17815/jlsrf-1-21 Journal of large-scale research facilities, 1, A3 (2015)

Figure 2: Schematic drawing of MIRA-1.

3.1.4 Analyzer

• 2 cavities
• 2 bender
• 3He-spin �lter

3.1.5 Detector

• 20 x 20 cm2 2-D PSD with 1 x 2 mm2 resolution
• 1 inch 3He �nger detector
• 20 x 20 cm2 2-D PSD, time resolution < 1 ps

3.2 MIRA-2

3.2.1 Primary beam

• Neutron guide: NL6-S
• Dimensions: 60 x 120 mm2 (width x height)
• Coating: sides m = 2.0, top/bottom m = 2

3.2.2 Monochromator

• Horizontal focussing HOPG ∆λ /λ ≈ 2%
• 3.5 Å < λ < 6 Å

3.2.3 Max. di�erential neutron �ux at sample

• 1 · 107 n cm-2s-1 at 4.7 Å (2015)
• 1 · 106 n cm-2s-1 polarised

3.2.4 Analyzer

• 2 cavities
• S-bender, transmission polariser
• 3He-spin �lter

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Journal of large-scale research facilities, 1, A3 (2015) http://dx.doi.org/10.17815/jlsrf-1-21

Figure 3: Schematic drawing of MIRA-2.

3.2.5 Detector

• 20 x 20 cm2 2-D PSD with 1 x 2 mm2 resolution
• 1 inch 3He �nger detector
• 20 x 20 cm2 2-D PSD, time resolution < 1 ps
• with low background < 0.1 cps

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	Introduction
	Typical Applications
	Technical Data
	MIRA-1
	Primary beam
	Monochromator
	Max. differential neutron flux at sample
	Analyzer
	Detector

	MIRA-2
	Primary beam
	Monochromator
	Max. differential neutron flux at sample
	Analyzer
	Detector