1. Christos Lamboudis HEP 17-20 April. Athens Study of MDT response to neutrons and possible ageing effects Do we really need to worry about neutrons? Do we really need to worry about neutrons? If so, then we have run some tests with real neutrons If so, then we have run some tests with real neutrons Where can we find proper neutron beam sources? Where can we find proper neutron beam sources? Detailed description of the beam facilities Detailed description of the beam facilities Conclusion - Proposal 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 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 expected neutron background rates sensitivity of all muon detector components, as a function of particle energy(lack of experimental data) sensitivity of all muon detector components, as a function of particle energy(lack of experimental data) neutron cross sections (gas mix.-materials..) 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. 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. Christos Lamboudis HEP 17-20 April. Athens 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 Van de Graaf type 5.5MV acceleration voltage 5.5MV acceleration voltage Deuteron beam path : analyzer magnet beam chopper switching magnet Ta collimator (2r=5mm) gas cell Deuteron beam path : analyzer magnet beam chopper switching magnet Ta collimator (2r=5mm) gas cell Gas cell dimensions : length (3.7-5.7cm) Gas cell dimensions : length (3.7-5.7cm) (stainless steel) ext.diameter (1cm) (stainless steel) ext.diameter (1cm) wall thickness (0.2mm) wall thickness (0.2mm) Gas cell entrance window : Mo/Ti foil (5/2.5mg/cm 2 ) Gas cell entrance window : Mo/Ti foil (5/2.5mg/cm 2 ) Pressure : ~ atm Pressure : ~ atm Beam stop : Pt 0.9 mm foil Beam stop : Pt 0.9 mm foil

7. Christos Lamboudis HEP 17-20 April. Athens The neutron production cell assembly

8. Christos Lamboudis HEP 17-20 April. Athens Properties of some (d,n) reactions Reaction D(d,n) 3 He D( 3 H,n) 4 He 7 Li(p,n) 7 Be 12 C(d,n) 13 N 14 N(d,n) 15 O 7 Li(d,n) 8 Be Q Value (MeV) 3,265 ± 0,018 17,578 -1,882 ± 0,002 -0,281 ± 0,003 5,1 15,0 E n0 for E d =0 (MeV) 2,45 (NCSR) 14,1 (NCSR) 0,12* 4,8 13,3

9. Christos Lamboudis HEP 17-20 April. Athens d+d total reaction cross section as a function of incident deuteron energy

10. Christos Lamboudis HEP 17-20 April. Athens d+t total reaction cross section as a function of incident deuteron energy

11. Christos Lamboudis HEP 17-20 April. Athens d+d neutron energy angular distribution

12. Christos Lamboudis HEP 17-20 April. Athens d+ 3 H neutron energy angular distribution

13. Christos Lamboudis HEP 17-20 April. Athens General layout of the PS213 experiment

14. Christos Lamboudis HEP 17-20 April. Athens N_TOF facility-CERN  Neutron beam line  Pb target

15. Christos Lamboudis HEP 17-20 April. Athens n_TOF : Basic Parameters Proton beam Proton beam momentum : 20GeV/c Proton beam momentum : 20GeV/c Intensity : 7 x 10 12 p/pulse (dedicated) or 4 x 10 12 p/pulse (parasitic) Intensity : 7 x 10 12 p/pulse (dedicated) or 4 x 10 12 p/pulse (parasitic) Repetition frequency : 1 pulse/2.4sec Repetition frequency : 1 pulse/2.4sec Spallation module Material : Lead Material : Lead X,Y,Z dimensions : 80 x 80 x 60 (cm 3 ) X,Y,Z dimensions : 80 x 80 x 60 (cm 3 ) TOF tube Total length : 199.607m (mostly stainless steel) Total length : 199.607m (mostly stainless steel) Internal diameter : [80 – 40] cm Internal diameter : [80 – 40] cm Two collimators used for beam modification Two collimators used for beam modification

16. Christos Lamboudis HEP 17-20 April. Athens Energy distribution of the neutrons at the exit of the Pb target (black) and the sample position of the EAR (red)

17. Christos Lamboudis HEP 17-20 April. Athens Beam profile

18. Christos Lamboudis HEP 17-20 April. Athens Neutron flux (EAR-1),using different experimental techniques 10 -2 110 2 10 4 10 6 10 8 E n (eV)

19. Christos Lamboudis HEP 17-20 April. Athens Conclusions Need for more experimental data Need for more experimental data TANDEM irradiation test (real time…), waiting for results! TANDEM irradiation test (real time…), waiting for results! n_TOF test n_TOF test In beam irradiation In beam irradiation 2 nd collimator area 2 nd collimator area