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Study of MDT response to neutrons and possible ageing effects

Study of MDT response to neutrons and possible ageing effects. Do we really need to worry about neutrons? If so, then we have run some tests with real neutrons Where can we find proper neutron beam sources? Detailed description of the beam facilities Conclusion - Proposal.

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Study of MDT response to neutrons and possible ageing effects

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  1. Study of MDT response to neutrons and possible ageing effects • Do we really need to worry about neutrons? • If so, then we have run some tests with real neutrons • Where can we find proper neutron beam sources? • Detailed description of the beam facilities • Conclusion - Proposal Christos Lamboudis HEP 17-20 April. Athens

  2. Are neutrons worth to bother? • Highly ionizing neutrons can produce charge, much larger compared with that of a muon • electronics recovery time? • detector’s lifetime? • Triggers induced by background neutrons? • Neutron interactions with detector wall materials? • Ageing effects? Christos Lamboudis HEP 17-20 April. Athens

  3. So, what we really have to know… • expected neutron background rates • sensitivity of all muon detector components, as a function of particle energy(lack of experimental data) • neutron cross sections (gas mix.-materials..) Christos Lamboudis HEP 17-20 April. Athens

  4. Need for proper neutron beam facility.Probably available: • NCSR Tandem(Van de Graaf 5.5MV) accelerator. info: neutron energy up to 27MeV site : Demokritos Institute, Athens-Greece (already running !!) • n_TOF facility (PS213 experiment, CERN) info: spallation neutron source with energy range from thermal to GeV site: TOF facility, CERN-Geneva Switzerland

  5. TANDEM T11/25 H.V.E.C 5.5MV Demokritos TANDEM accelerator Christos Lamboudis HEP 17-20 April. Athens

  6. TANDEM key features • Van de Graaf type • 5.5MV acceleration voltage • Deuteron beam path : analyzer magnet beam chopper switching magnet Ta collimator (2r=5mm) gas cell • Gas cell dimensions : length (3.7-5.7cm) (stainless steel) ext.diameter (1cm) wall thickness (0.2mm) • Gas cell entrance window : Mo/Ti foil (5/2.5mg/cm2) • Pressure : ~ atm • Beam stop : Pt 0.9 mm foil

  7. The neutron production cell assembly

  8. Properties of some (d,n) reactions Q Value (MeV) 3,265 ± 0,018 17,578 -1,882 ± 0,002 -0,281 ± 0,003 5,1 15,0 En0 for Ed=0 (MeV) 2,45 (NCSR) 14,1 (NCSR) 0,12* 4,8 13,3 Reaction D(d,n)3He D(3H,n)4He 7Li(p,n)7Be 12C(d,n)13N 14N(d,n)15O 7Li(d,n)8Be

  9. d+d total reaction cross section as a function of incident deuteron energy

  10. d+ttotal reaction cross section as a function of incident deuteron energy

  11. d+d neutron energy angular distribution

  12. d+3H neutron energy angular distribution

  13. General layout of the PS213 experiment

  14. N_TOF facility-CERN • Neutron beam line • Pb target

  15. n_TOF : Basic Parameters Proton beam • Proton beam momentum : 20GeV/c • Intensity : 7 x 1012 p/pulse (dedicated) or 4 x 1012 p/pulse (parasitic) • Repetition frequency : 1 pulse/2.4sec Spallation module • Material : Lead • X,Y,Z dimensions : 80 x 80 x 60 (cm3) TOF tube • Total length : 199.607m (mostly stainless steel) • Internal diameter : [80 – 40] cm • Two collimators used for beam modification

  16. Energydistribution of the neutrons at the exit of the Pb target (black) and the sample position of the EAR (red)

  17. Beam profile

  18. Neutron flux (EAR-1),using different experimental techniques 10-2 1 102 104 106 108 En(eV)

  19. Conclusions • Need for more experimental data • TANDEM irradiation test (real time…), waiting for results! • n_TOF test • In beam irradiation • 2nd collimator area

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