Inverted geometry time-of-flight spectrometer



Fig. 1. The scheme of an inverted geometry NERA spectrometer

1 – IBR-2 reactor core
2 – thermal and cold moderators of radial horizontal beamlines 7-11 and tangential beamlines 1–9
3 – beam shutter
4 – fast neutron background chopper
5 – common vacuum splitter of three neutron beams by Ni-mirror neutron guides
6 – l-chopper of beamline 7b
7 – vacuum Ni-mirror guide tube of neutron beamline 7b
8 – vacuum sections of beamline 7b
9-10 – monitor and diaphragms of incident beam 7b, respectively
11 – sample position
12 – NPD sections
13 – INS and QENS sections of the NERA spectrometer.


Instrument Responsible:
Goremychkin Eugeny A.
Russia, Moscow reg., Dubna, Joliot-Curie str., 6
tel. +7 (49621) 6-54-86
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.


Instrument Co-Responsible:
Dorota Chudoba
Russia, Moscow reg., Dubna, Joliot-Curie str., 6
tel. +7 (49621) 6-50-96
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.


Inelastic Scattering Group Staff


Main research fields:

1. Dynamics and structure of condensed matter, particularly, of the substances exhibiting phase polymorphism;

2. Investigation of substances in which phase transitions are accompanied by changes in the structure, lattice dynamics or in the character of stochastic motion of molecules or molecular groups.


NERA - a multi-purpose inverse geometry spectrometer

NERA is an indirect geometry spectrometer designated predominantly for the study of molecular dynamics. The instrument is located at a distance of 100 m from the ambient water moderator at the end of the neutron guide. The recently installed cold (30K) neutron source increased the luminosity of the spectrometer by a factor of five at low energy transfer. The combination of a cooled beryllium filter and pyrolytic graphite analyzer provides the energy resolution at the elastic position ~ 0.7 meV with good intensity in the energy range up to ~ 120 meV. NERA can also be used as a diffractometer; the range of detected scattering angles provides good resolution in the Q-range (0.7 – 21 Å-1). The sample environment system on NERA permits inelastic and diffraction experiments at low temperatures (5K-300K) and high pressures up to 400 MPa.
The scientific program on NERA includes studies of hydrogen-bonded systems, biologically active materials, organic compounds; study of properties of dynamic complexes with transfer of electric charge, etc.

Fig. 2. Layout of neutron scattering detectors.

F1 – sample
2 – Be-filters
3 – collimators
4 – 3He detectors (INS and QNS)
5 – PG analyzers (INS)
6 – single crystal analyzers (QNS)
7 – detectors for high intensity diffraction
8 – diffraction detectors with good collimation
9 – spectrometer shielding
10 – Ni-coated mirror neutron guide in a vacuum tube
11-12 – diaphragms and monitor of incident beam 7b, respectively
13 – vacuum neutron guide.

Fig.3. View of NERA spectrometer


Basic parameters 


Neutron guide Mirror, vacuum
Guide aperture 50×160mm2
Thermal neutron flux at sample position 4.6×106n/cm2/s
Wavelength range 0.8-7.0 Å
Scattering angles range 10o-170o
Energy transfer range (INS) 1-130 meV
Solid angle for INS  ~ 0.2  sr 
Momentum transfer range (QNS) 0.1-3.0 Å-1
Moderator - sample distance 109.5 m
Sample - detector distance 0.815 m (INS with Be-filter)
  1.015 m (INS with single crystal)
  1.745 m (high-resolution QNS)
  1.415 m(neutron diffraction)
Inelastic scattering see Fig. 4
Quasielastic scattering DE=40-600 µeV
Neutron diffraction D d/d=0.4% for l>1Å
Sample environment Closed-cycle helium refrigerators (4-300 K and 100-400 K). High-pressure cell (up to 10 kbar)


Fig. 4. Resolution for Inelastic scattering.