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.

IN16B project

Within the framework of the ILL Millennium Project we are building the new backscattering spectrometer IN16B. Guided 120 m from the reactor cold source the neutrons will be focused onto a phase space transformation chopper located inside the secondary spectrometer of IN16B. This chopper fulfils several functions: besides its classical reflector) that combines perfect backscattering with focusing optics, the PST chopper also optimizes the deflected beam for the doppler monochromator.

This is a real challenging project from the technical point of view. Indeed, it implies for example the design of a movable aluminum vessel (under vacuum) of 35m3 with a weight of weight 20 tons with shielding and the design of a PST chopper which will require the world highest acceleration.

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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.

LAGRANGE Project

BPC participates in the project of the design of IN1-LAGRANGE. This new 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 from the elliptical shape of the analyzer. As the sample and counter are placed at the foci positions, sample and counter are the optical image from each other. <nobr> </nobr> <nobr>With this project, we expect to increase the count rate by a factor of 5 and to lower the background by a factor of 10 and to improve the resolution by a factor of 4.

To reach the expected performances, an optimization of the filter thickness is needed. Calculations are performed to benchmark the models with the neutron measurements made on a beryllium sample and then extrapolate the results for the cylindrical filter which will be integrated on IN1.

Cold neutron sources

In collaboration with the Reactor Division, the BPC is in charge of improvement studies of the existing neutron cold sources of ILL. Basing the improvements on MCNP neutronic calculations, we expect significant enhancement of ILL cold neutron fluxes.

The Vertical Cold Source

The whole 'in-pile' cold source has been modelised by MCNP 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 of the neutron brightness up to 2.32 times the actual values (depending on the wavelength and on the position).