Course on Unfolding of Bonner Sphere Spectrometer Neutron Measurements

Europe/Zurich
Bildungszentrum OSGA/EG06 (Paul Scherrer Institut)

Bildungszentrum OSGA/EG06

Paul Scherrer Institut

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

 

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.

    • 8:30 AM 9:00 AM
      Check-in 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 9:00 AM 9:45 AM
      1. Introduction to unfolding 45m Bildungszentrum OSGA/EG06 (PSI)

      Bildungszentrum OSGA/EG06

      PSI

      a. What is unfolding and why is it difficult?
      b. Conceptual issues, mathematical issues
      c. Some examples of unfolding for particle detectors
      d. Review of different approaches to the problem of unfolding

      Speaker: Dr Marcel Reginatto (PTB)
    • 9:45 AM 10:30 AM
      2. Bonner spheres I 45m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      Basic principles, neutron thermal counters, experimental aspects, standard and extended range Bonner sphere spectrometers, etc.

      Speaker: Dr Neil Roberts (NPL)
    • 10:30 AM 11:00 AM
      Coffee Break 30m Cafeteria OASE (PSI)

      Cafeteria OASE

      PSI

    • 11:00 AM 11:50 AM
      The role of prior information in unfolding Bonner sphere data 50m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Why is it important?
      b. Types of prior information
      c. How to incorporate prior information into unfolding methods
      d. Some statistics relevant to the topic (counting statistics,
      chi-squared, etc.)
      e. How to choose initial estimates of spectra, etc. Sensitivity
      analysis

      Speaker: Dr Marcel Reginatto (PTB)
    • 11:50 AM 1:30 PM
      Lunch Break 1h 40m OASE (Paul Scherrer Institute)

      OASE

      Paul Scherrer Institute

    • 1:30 PM 3:00 PM
      Installation of the unfolding programs and of the Bayesian program 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speakers: Dr Marcel Reginatto, Dr Eike Hohmann, Dr Benjamin Lutz
    • 3:00 PM 3:30 PM
      Coffee Break 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 3:30 PM 5:00 PM
      Simple preliminary exercises (to be determined, perhaps measurements at a reactor) 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Description of the experimental set-ups
      b. What problems may one encounter with the examples?
      c. Real or simulated data to be used for the unfolding

      Speakers: Dr Marcel Reginatto (PTB), Dr Eike Hohmann, Dr Benjamin Lutz
    • 9:00 AM 9:45 AM
      Validation of Bonner sphere response functions with sources and mono-energetic beams. 45m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speaker: Dr Neil Roberts (NPL)
    • 9:45 AM 10:30 AM
      Review of unfolding methods, part I 45m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Why direct inversion fails
      b. Direct inversion and “fix it” approaches
      c. Regularization methods
      d. Linear least-square methods
      e. Iterative methods
      f. Other approaches: Stochastic methods, neural networks,
      etc.

      Speaker: Dr Marcel Reginatto (PTB)
    • 10:30 AM 11:00 AM
      Coffee Break 30m Cafeteria OASE (Paul Scherrer Institute)

      Cafeteria OASE

      Paul Scherrer Institute

    • 11:00 AM 11:50 AM
      Review of unfolding methods, part II 50m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Maximum entropy unfolding
      b. Bayesian Parameter estimation and uncertainties

      Speaker: Dr Marcel Reginatto (PTB)
    • 11:50 AM 1:30 PM
      Lunch Break 1h 40m Restaurant OASE (Paul Scherrer Institute)

      Restaurant OASE

      Paul Scherrer Institute

    • 1:30 PM 3:00 PM
      Some relatively simple Bonner sphere unfolding problems (to be determined, perhaps measurements at an accelerator behind shielding) 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Description of the experimental set-ups
      b. What problems may one encounter with the examples?
      c. Real or simulated data to be used for the unfolding

      Speakers: Dr Marcel Reginatto (PTB), Dr Eike Hohmann (Paul Scherrer Institut), Dr Benjamin Lutz
    • 3:00 PM 3:30 PM
      Coffee Break 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 3:30 PM 5:00 PM
      Some relatively simple Bonner sphere unfolding problems (to be determined, perhaps measurements at an accelerator behind shielding) 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speakers: Dr Marcel Reginatto (PTB), Dr Eike Hohmann (Paul Scherrer Institut), Dr Benjamin Lutz
    • 9:00 AM 10:30 AM
      Special topics: Bonner spheres II: Calculation of the response function with Monte Carlo codes, problem of the cross sections at high energy 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      1. Bonner spheres II: Calculation of the response function with Monte Carlo codes, problem of the cross sections at high energy

      2. Measurement of cosmic ray induced neutrons

      Speaker: Dr Vladimir Mares
    • 10:30 AM 11:00 AM
      Coffee Break 30m Cafeteria OASE (Paul Scherrer Institute)

      Cafeteria OASE

      Paul Scherrer Institute

    • 11:00 AM 12:00 PM
      Typical neutron spectra of workplace fields, review of existing reference facilities 1h Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Reference fields (sources, monoenergetic beams, high
      energy quasi-monoenergetic beams)
      b. Workplace and other fields (to be determined)

      Speaker: Dr Neil Roberts (NPL)
    • 12:00 PM 1:30 PM
      Lunch Break 1h 30m Restaurant OASE (Paul Scherrer Institute)

      Restaurant OASE

      Paul Scherrer Institute

    • 1:30 PM 3:00 PM
      Approaches to the unfolding of Bonner sphere measurements for the validation of Monte Carlo simulations, focusing on the special case of Bonner sphere measurements at proton therapy facilities 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      a. Description of the experimental set-ups
      b. What problems may one encounter with the examples?
      c. Real or simulated data to be used for the unfolding

      Speakers: Dr Marcel Reginatto (PTB), Dr Eike Hohmann, Dr Benjamin Lutz
    • 3:00 PM 3:30 PM
      Coffee Break 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 3:30 PM 5:00 PM
      A Bayesian analysis of one of these examples 1h 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      A Bayesian analysis of one of these examples

      Speakers: Dr Marcel Reginatto (PTB), Dr Eike Hohmann, Dr Benjamin Lutz
    • 6:00 PM 8:30 PM
      Workshop Dinner 2h 30m Restaurant OASE (Paul Scherrer Institute)

      Restaurant OASE

      Paul Scherrer Institute

    • 9:00 AM 9:45 AM
      Special topics: Facilities representing the new generation of particle acceleration technology (high power lasers, free electron lasers), other facilities 45m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland

      Facilities representing the new generation of particle acceleration technology (high power lasers, free electron lasers), other facilities

      Speaker: Dr Veronika Olšovcová,
    • 9:45 AM 10:30 AM
      Dead time correction, pulsed neutrons, etc. 45m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speaker: Prof. Marco Caresana
    • 10:30 AM 11:00 AM
      Coffee Break 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 11:00 AM 11:30 AM
      Questions from the participants and further discussion with experts about topics of interest, feedback from the participants, closing of the course 30m Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speaker: All lecturers
    • 11:30 AM 12:30 PM
      Visit of a facility Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

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