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PN1 - RED magnet

A series of short movies showing how neutron experiments are prepared or performed. Some of these movies have an historical interest since they captured important moments in the life of the ILL.

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Films and animations

PN1 - From one experiment to the other

PN1 (also called LOHENGRIN) is the world-leading fission fragment separator.

A target of a fissile isotope placed near the core of the ILL reactor in a thermal neutron flux of 5.3 x 1014 n cm-2 s-1 emits a variety of fission products. These radioactive isotopes originating from the target are separated (sorted) by LOHENGRIN which is nothing else than an unusually large mass spectrometer i.e. a combination of a magnetic and an electric sector field whose deflections are perpendicular to each other. This makes it possible to study mass, kinetic energy and charge distribution for products from thermal neutron induced nuclear fission at very high resolution.

In the last part of their flight through LOHENGRIN, fission products are focalized on an arrangement of detectors by the RED magnet (Reverse Energy Dispersion dipole magnet). It is this device which is shown below.

The main applications of PN1 are:
- the study of the decay of exotic neutron-rich nuclei (e.g. better understanding of supernova explosions)
- fission process investigation (e.g. better understanding of different fissile systems from binary and ternary fission reactions)
- Practical applications (e.g. study of diffusion of actinides in different surrounding materials).



   "The recoil separator Lohengrin: Performance and special features for experiments."
    P. Armbruster, M. Asghar, J. P. Bocquet, R. Decker, H. Ewald, J. Greif, E. Moll, B. Pfeiffer, H. Schrader, F. Schussler, G. Siegert and H. Wollnik (1976) Nucl. Instr. Meth. 139, 213-222.

   "Reduction of energy dispersion on a parabola mass spectrometer."
    Fioni G. , Faust H.R. , Gross M. , Hesse M. , Armbruster P. , Gönnenwein F. , Muenzenberg G. (1993) Nuclear Instruments and Methods in Physics Research A 332, 175-180.

The video below was shot in the RED magnet housing by 28 May 2007, i.e. between experiment 3-01-498 (Beta-gamma spectroscopy of very neutron-rich Ge, As and Se isotopes) and experiment 3-01-501 (Determination of mass and nuclear charge of heavy fission fragments from fission of Pu isotopes). It shows how the complicated set of measuring devices and detectors required for the first experiment is removed and then the equiment required for the second experiment is installed. This has no other goal than showing you that nuclear physicists must be slim, well trained to climb and, in addition to physics, must be good at screwing and unscrewing !

Movie by Alain Filhol

©2007 Institut Laue-Langevin, Grenoble, France

Movie files (768x576 pixels, duration 4'11): .mp4 (45 Mb), .webm (48 Mb)
Movie files (640x480 pixels, duration 4'11): .mp4 (26 Mb), .webm (35 Mb).

Updates: A. Filhol, 20 Dec. 2007, 3 may 2012.