Course on Unfolding of Bonner Sphere Spectrometer Neutron Measurements

Bildungszentrum OSGA/EG06 (Paul Scherrer Institut)

Bildungszentrum OSGA/EG06

Paul Scherrer Institut

Forschungsstrasse 111 5232 Villigen PSI Switzerland
Eike Hohmann (Paul Scherrer Institut)


Bonner sphere spectrometers (BSS) are widely used for measuring the spectral neutron distribution. The BSS can determine neutron spectra over a wide energy range covering up to 12 orders of magnitude and it has been used for the measurement of neutron spectra at many different types of facilities, such as reactors, accelerators, and medical facilities. The analysis of the measured data, however, requires unfolding methods, which have to be used carefully to obtain reliable results.

The course provides an introduction to unfolding for BSS with practical applications.

The emphasis is on unfolding exercises using different measurement scenarios. The course is intended for those who do spectrometry in neutron or mixed neutron/photon fields and need to analyze their data using unfolding procedures.

This course is organized as part of EURADOS. 
The main part of the course is carried out by Marcel Reginatto (PTB), Eike Hohmann (PSI) abd Veronique Lacoste (IRSN) with additional contributions from members of EURADOS WG11.


The course is a four-day training course on neutron spectra unfolding measured with Bonner sphere spectrometers (BSS), organised by the department for radiation safety and security of the Paul Scherrer Institut (PSI) in collaboration with the neutron radiation department of the Physikalisch-Technische Bundesanstalt (PTB) and EURADOS.

The emphasis of the course is on practical aspects. The course is intended for those who do neutron spectrometry with  BSS in neutron or mixed neutron/photon fields and need to analyze their data using unfolding procedures.

In the morning sessions, there will be a series of lectures which will provide an introduction to unfolding as well as allow for discussions on the theory of unfolding. In the afternoon sessions, the participants will work on specific examples using two methods: MAXED and GRAVEL (See download section for references and additional information). There will also be an introduction to the use of a Bayesian approach for analyzing BSS data.

The course will take place at the PSI Campus with a maximum of 20 participants.  Depending on the current pandemic situation, a change to an online training course may be possible – a hybrid event is not being planned.