Commissioning of the n_TOF second experimental area at CERN

1. Commissioning of the n_TOF second experimental area at CERN Lucia Anna Damone, INFN Bari, on behalf of the n_TOF Collaboration 101o Congresso Nazionale della Societa’ Italiana di Fisica, Roma, 21-25 Settembre 2015

2. Outline • The n_TOF project • The facility • Flux measurement • Beam profile measurement • Conclusions L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

3. The n_TOF Collaboration CERN TechnischeUniversitat Wien Austria IRMM EC-Joint Research Center, Geel Belgium IN2P3-Orsay, CEA-Saclay France KIT – Karlsruhe,Goethe University, Frankfurt Germany Univ. of Athens, Ioannina, Demokritos Greece INFN Bari, Bologna, LNL, LNS, Trieste, ENEA – BolognaItaly Tokyo Institute of Technology, JAEA Japan ITN LisbonPortugal Charles Univ. (Prague) Czech Republic Univ. of LodzPoland IFIN – BucarestRumania INR – Dubna*, IPPE – Obninsk* Russian Fed. CIEMAT, Univ. of Valencia, Santiago de Compostela, University of Cataluna, Sevilla Spain University of Basel, PSISwitzerland Univ. of Manchester, Univ. of York UK ~30 Institutions >100 Researchers + Newcomers High accuracy measurements of neutron induced reaction cross-sections (n,f), (n,cp), (n,g) L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

4. n_TOF measurements at glance Nuclearenergy (fissionproducts & Structural material) Nuclear Astrophysics (stellar nucleosynthesis and BBN) Astrophysics Advancednuclearreactors (actinides) L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

5. The n_TOF facility (1/2) 185 m flight path n_TOF is a spallation neutron source based on 20 GeV/cprotons from the CERN PShitting a Pb block (~360 neutrons per proton). EAR1 Experimental area at 185 m Booster 1.4 GeV PS 20 GeV Main feature: • extremely high instantaneous neutron flux (105 n/cm2/pulse). • very convenient for measurements of radioactive isotopes, • low cross sections, • Isotope available in small quantity Linac 50 MeV L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

6. The n_TOF facility (2/2) Experimental Area 2 (EAR2) is a new measuring station placed (vertically) at 20 m from spallation target. • Higher fluence, by a factor of 30, relative to EAR1. • The shorter flight path implies a factor of 10 smaller time-of-flight. • Global gain by a factor of 300 in the signal/background ratio forradioactive isotopes! EAR2 The huge gain in signal-to-background ratio in EAR2 allows to measure radioactive isotopes with half lives as low as a few days. 20 m EAR1 20 GeV/c protons Spallation Target 185 m L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

7. Reaction Energy range of standard Commissioning of EAR2 The new beam line has been characterized in terms of flux and beam profile by means of several detection systems, namely silicon based devices and gaseous detectors. The detectors are equipped with different neutron converters placed in front of the sensible layer or volume By combining the results of different detection system is possible to reach accuracy as low as few percent (or less). FUNDAMENTAL TO NORMALIZE DATA L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

8. Silicon Monitor (SiMon2) • LiF converter 105 mg/cm2 • 4 single pad silicon detectors 3x3 cm2 Si Si t 6LiF a neutrons Setup for flux measurement @n_TOF-EAR2 MGAS detectors (LiF, 235U,10B) few mm gas gap L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

9. Analisys details GEANT4 simulation to determine efficiency Selection cuts to reject background events t a L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

10. Results for flux measurements Agreement between detectors is being investigated and an official evaluation of the n_TOF flux in experimental area 2 is going to be released. At this stage of the analysis the agreement between detectors varies from 1% to 8% L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

11. Comparison neutron flux EAR2/EAR1 x30 Possibility to study isotopes with very short half life (days) L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

12. Beam profile detector The spatial distribution on neutrons as a function of energy has been measured by means of a double side silicon strip detector (DSSSD). • 16 x 16 Si sensor strips • 3 mm wide strips, 500 mm thick • 50 x 50 mm² X-Y grid • LiF converter • Selection of tritons L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

13. Beam profile measured The neutron beam has a Gaussian profile in transversal plane. L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

14. Beam profile measured L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015

15. Conclusions • There is need of accurate new dataon neutron cross-section both for nuclearastrophysics and advanced nuclear technology (and nuclear medicine, fundamental physics..) • Since 2001, n_TOF@CERN has provided an important contribution to the field, with an intense activity on capture, fission and n-charged particle measurements. • A second new (andmore intense flux) experimental area is now available. • The commissioning ofEAR2has been performed in 2014, particularly in terms of energy and spatial distribution of neutrons. • The measurements confirm the enhancement of flux in EAR2 with respect EAR1. • EAR2 opens new perspectives for frontier measurements on short-lived radionuclides. L. Damone, Commissioning of the n_TOF second experimental area at CERN, SIF 2015, Roma 21-25 Settembre 2015