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Accélérateur Linéaire et Tandem à Orsay (ALTO)
Hosting Legal Entity
French National Center for Scientific Research / Centre National de la Recherche Scientifique (CNRS)
3 Michel-Ange street, CNRS, Paris, PO: 75794, Ile-de-France (France)
French National Center for Scientific Research / Centre National de la Recherche Scientifique (CNRS)
3 Michel-Ange street, CNRS, Paris, PO: 75794, Ile-de-France (France)
University of Paris-Saclay
University of Paris-Sud
15 rue Georges Clemenceau, Institut de Physique Nucléaire Orsay - Université Paris Sud Building 109, Orsay, PO: 91406 (France)
Type Of RI
Coordinating Country
Current Status:
Operational since 2012
Scientific Description
The ALTO facility consists of two accelerators in the same area: a tandem accelerator dedicated to stable (ions and cluster) beam physics and a linear electron accelerator dedicated to the production of radioactive beams. This gives a unique opportunity to have in one place cluster beams for interdisciplinary physics and stable and radioactive beams for astrophysics and nuclear physics. The ALTO facility can deliver radioactive beams, stable beams and cluster beams having a large physics case from nuclear structure to atomic physics, cluster physics, biology and nanotechnology.

RI Keywords
Cluster beams, Astro-chemistry, Nuclear structure, Electroestatic accelerators, Stable beams, Radioactive beams, Nuclear astrophysics, Fission fragments
RI Category
Nuclear Research Facilities
Scientific Domain
Engineering and Energy
Chemistry and Material Sciences
Physics, Astronomy, Astrophysics and Mathematics
ESFRI Domain
Physical Sciences and Engineering
Access to Detector Laboratory

The Detector Laboratory at IPN Orsay belongs to the most advanced laboratory in Europe for testing and repair of large volume HPGe detectors for gamma arrays. ALTO is the home base of the French–UK Ge pool testing and repairing the Ge detectors for JUROGAM (Jyvaskyla) and Dubna (Russia).

Access to Laser Laboratory RIALTO

A Laser laboratory is installed at the ALTO facility in order to test the new ionisation scheme for the production of very pure radioactive ion beams and to make the RIALTO laser ion source work.

Access to Target Laboratory

Target Laboratory at IPN Orsay for the production of thin films to be used as targets in nuclear physics experiments, solid state and applied research.


The stable nuclear beams are delivered by the Tandem, an electrostatic accelerator. Most of the elements in the periodic table can be produced as a beam by this accelerator. Routinely, about 75 different nuclear beams are produced ranging from p to Au. The Tandem also delivers cluster beams and micro-droplets. Furthermore the Tandem doesn’t deliver only stable beams : the beams of interest 14C and 48Ca are also produced. The team of ALTO runs the Tandem according to the request of the scheduled experiments.The stable beams are distributed among 6 experimental setups : SPLIT POLE, BACCHUS, ORGAM, AGAT, SIFAGA and beamline 410. Furthermore, an irradiation station in the accelerator hall can be used to send the selected beams on different material samples for various applications.

Split Pole

Split Pole is a magnetic spectrometer used for the detection and the measurement of the impulsion of charged particle reactions in “two body” reactions with a very high resolution. This spectrometer is now used intensively for nuclear astrophysical studies.


OSCAR (Orsay Segmented Clover Array) is a Ge detector consisting of 4 Ge clovers placed in close geometry in order to study low multiplicity decay of very exotic nuclei. It is associated mainly with the PARRNe ISOL line.


ORGAM is a Ge multidetector associated with the BACCHUS spectrometer and ancillary charged particle detectors for the study of deep inelastic reactions and fusion evaporation.


DIESE, DIESE X, ESKIMO are dedicated set-ups for irradiation with cluster beams (CnHm, C60, Aun). Among the various possible projectiles, clusters have the unique property of depositing important energy densities in solids, much more than with the use of atomic projectiles. The consequences are structural modifications in solids and amplifications of secondary emissions. This leads to very interesting and dynamic studies in nanotechnology.


SIHL is an off-line separator dedicated for the testing of and research and development on target ion sources used at PARRNe. This off-line separator is connected to the laser laboratory for testing new ionisation schemes used for radioactive ion beams.


BACCHUS is a 180° magnetic spectrometer designed to suppress the primary beam. This spectrometer is mainly dedicated to heavy ion studies.


AGAT is a new generation of detection apparatus used in Cluster Physics developed at the ALTO facility. Electronic signals delivered by an epitaxial silicon detector were digitalized and used as identifier for cluster fragments. With such a device, AGAT multidetector is able to resolve all partitions of Cn clusters up to n=9. This set up is mainly used for atomic astrophysical studies.


PARRNe is an isol line (with up to 5 lines) dedicated to the study of very neutron-rich nuclei produced by fission (neutron induced or photofission). Fast tape transport systems are available for studying short lived nuclei. Several target ion source ensembles are developed at the facility: surface ionisation, laser ion source, febiat ion source ….

European Nuclear Science and Applications Research (ENSAR)
Date of last update: 01/07/2019
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