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.

    • 1
      Check-in Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 2
      1. Introduction to unfolding 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)
    • 3
      2. Bonner spheres I 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 Véronique Lacoste (IRSN)
    • 10:30 AM
      Coffee Break Cafeteria OASE (PSI)

      Cafeteria OASE

      PSI

    • 4
      The role of prior information in unfolding Bonner sphere data 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
      Lunch Break OASE (Paul Scherrer Institute)

      OASE

      Paul Scherrer Institute

    • 5
      Installation of the unfolding programs and of the Bayesian program 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
      Coffee Break Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 6
      Simple preliminary exercises (to be determined, perhaps measurements at a reactor) 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
    • 7
      Validation of Bonner sphere response functions with sources and mono-energetic beams. Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speaker: Dr Véronique Lacoste (IRSN)
    • 8
      Review of unfolding methods, part I 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
      Coffee Break Cafeteria OASE (Paul Scherrer Institute)

      Cafeteria OASE

      Paul Scherrer Institute

    • 9
      Review of unfolding methods, part II 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
      Lunch Break Restaurant OASE (Paul Scherrer Institute)

      Restaurant OASE

      Paul Scherrer Institute

    • 10
      Some relatively simple Bonner sphere unfolding problems (to be determined, perhaps measurements at an accelerator behind shielding) 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
      Coffee Break Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 11
      Some relatively simple Bonner sphere unfolding problems (to be determined, perhaps measurements at an accelerator behind shielding) 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
    • 12
      Special topics: 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
      Coffee Break Cafeteria OASE (Paul Scherrer Institute)

      Cafeteria OASE

      Paul Scherrer Institute

    • 13
      Typical neutron spectra of workplace fields, review of existing reference facilities 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 Véronique Lacoste (IRSN)
    • 11:50 AM
      Lunch Break Restaurant OASE (Paul Scherrer Institute)

      Restaurant OASE

      Paul Scherrer Institute

    • 14
      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 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
      Coffee Break Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 15
      A Bayesian analysis of one of these examples 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
      Workshop Dinner Restaurant OASE (Paul Scherrer Institute)

      Restaurant OASE

      Paul Scherrer Institute

    • 16
      Special topics 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

      Speakers: Eike Hohmann, Dr Veronika Olšovcová,
    • 17
      Dead time correction, pulsed neutrons, etc. Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

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

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
    • 18
      Questions from the participants and further discussion with experts about topics of interest, feedback from the participants, closing of the course Bildungszentrum OSGA/EG06

      Bildungszentrum OSGA/EG06

      Paul Scherrer Institut

      Forschungsstrasse 111 5232 Villigen PSI Switzerland
      Speaker: All lecturers