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Innovative Projects

The "Projects and Calculations" labs (BPC) has two main roles : achievement of innovative projects and carrying out complex calculations in many physical fields for all ILL divisions.

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Innovative Projects

The BPC is in charge of most of ILL's innovative project work from the engineering point of view. Indeed, it has experience and skills in many technical fields.



Instrument IN16B

The BPC is collaborating on the construction of the new backscattering spectrometer IN16B, one of the ILL's Millennium Programme projects. Neutrons are guided 120 m from the reactor cold source for focusing on a phase-space transformation chopper located inside the secondary spectrometer of IN16B. This chopper fulfils several functions: besides its classical reflector, combining perfect backscattering with focusing optics, the PST chopper also optimises the deflected beam for the doppler monochromator.

This project is challenging from the technical point of view. It implies the design of a 35m3 movable aluminium vessel (under vacuum) weighing 20 tons with its shielding, as well as the design of a PST chopper achieving record acceleration speeds.

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The IN16B project team has designed a novel concept to retain the crystals under high centrifugal accelerations. We designed and tested a compact disc which requires higher accelerations than realised anywhere else in the world. The in-house design of the cassettes that hold a ‘sandwich’ of crystals, spacers and an absorber had therefore to be validated by extensive testing, that were carried out in-house by ILL’s technical department.  The safety margin was set 1000 rpm above the nominal rotation speed (6920 rpm). With these requirements fatigue tests, with more than 200 cycles, have been successfully carried out thus validating a PST nominal functioning of 20 years. After passing the cassette tests we now launch the production phase of the PST chopper.


The BPC is also working on the design of IN1-LAGRANGE. This new instrument configuration will enhance and replace the present IN1-BeF configuration used for high energy neutron spectrometry. Neutrons which are inelastically scattered by the sample are filtered by a beryllium filter, then selected and redirected towards a neutron counter by an analyzer. The innovation comes from the cylindrical symmetry and elliptical shape of the analyzer. As the sample and counter are placed at the foci positions, sample and counter form an optical image of eachother. With this project, we expect to increase the count rate by a factor of 5, whilst lowering the background by a factor of 10 and improving resolution by a factor of 4.

To reach the performances expected, we need to optimise the filter thickness. We perform calculations to benchmark the models with neutron measurements taken on a beryllium sample; we then extrapolate the results for the cylindrical filter to be integrated on IN1.

Cold neutron sources

In collaboration with the Reactor Division, the BPC is responsible for studies to improve ILL's existing neutron cold sources. We are basing our approach on MCNP neutronic calculations and expect significant enhancements to ILL's cold neutron fluxes.

The Vertical Cold Source

The whole 'in-pile' cold source has been modeled using the MCNP software package, in order to get the cold neutron brightness as a function of wavelength. The actual configuration calculation results are in good agreement with former calculations (by P.Ageron) and measurements.

By changing the re-entrant hole geometry we expect an increase in neutron brightness by up to 2.32 times the actual values (depending on the wavelength and position).




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