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nTOF New Target Panel Review Meeting

nTOF New Target Panel Review Meeting. nTOF New Target experimental requirements nTOF_Ph2 Collaboration E. Gonzalez (CIEMAT). CERN February 14th, 2008. n _TOF experiments 200 2 - 4. C apture 151 Sm 204,206,207,208 Pb, 209 Bi 232 Th 24,25,26 Mg 90,91,92,94,96 Zr, 93 Zr 139 La

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nTOF New Target Panel Review Meeting

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  1. nTOF New Target Panel Review Meeting nTOF New Target experimental requirements nTOF_Ph2 Collaboration E. Gonzalez (CIEMAT) CERN February 14th, 2008

  2. n_TOF experiments 2002-4 Capture 151Sm 204,206,207,208Pb, 209Bi 232Th 24,25,26Mg 90,91,92,94,96Zr, 93Zr 139La 186,187,188Os 233,234U 237Np,240Pu,243Am Fission 233,234,235,236,238U 232Th 209Bi 237Np 241,243Am, 245Cm • Measurements of neutron cross sections relevant for Nuclear Waste Transmutation and related Nuclear Technologies • Th/U fuel cycle (capture & fission) • Transmutation of MA (capture & fission) • Transmutation of FP (capture) • Cross sections relevant for Nuclear Astrophysics • s-process: branchings • s-process: presolar grains • Neutrons as probes for fundamental Nuclear Physics • Nuclear level density & n-nucleus interaction

  3. n_TOF beam characteristics • Capture and fission beams: • =4 cm beam • =8 cm beam • 0.1 eV up to 1 GeV • DE/E ~ 1·10-4 in the RRR Performance Report, CERN-INTC-2002-037, January 2003,CERN-SL-2002-053 ECT

  4. Resolution • The resolution experiences a peak + a tail due to the peculiarity of the moderation process of the lead + water moderator target • Δlwas represented with 2 ways: (i) as the sigma obtained by a fit on the peak of a small energy interval (20 bpd), (ii) as the RMS of the l distribution over the same energy interval

  5. n_TOF experiments 2008-… Capture Stable Isotopes: Mo,Bi, Ru: r-process residuals Fe, Ni, Zn, Se: s-process and structural materials 234,236U, 231,233Pa: Th/U fuel cycle 239,240,242Pu,241,243Am, 245Cm: transmutation of minor actinides Fission 231Pa,234,235,236,238U 241Pu,245Cm,241,243Am, 244,245Cm 234U: study of vibrational resonances below the bareer

  6. The (future) second n_TOF experimental area Newexperimentalarea at 20 m n_TOF target Experimental area at 185 m Flight-path length : ~20 m at 90° respect to p-beam direction 100 times more intense! n_TOF-Ph2

  7. After nearly 4 years of technical stop because the problems with the spallation target, nTOF needs urgently to restart measurements with experimental conditions that are as good or better than in 2004. The main requirements to the new nTOF spallation target are: • Keep the original level of neutron flux intensity on the measurement station (the protonpulse amplitude should be maintained although small reduction on its frequency can be acceptable if needed to limit the total power deposited in the target down to safe thermo-mechanical limits) • Same level of neutron flux quality on the measurement station (Neutron spectra, minimum resonant structures, time resolution function) • Compatible with minimization of in-beam photon contamination • Compatible with the possibility of a second experimental area in the vertical direction. • Compatible with CERN Safety Regulations and Budget • Available for physics measurements within 2008

  8. After the previous Panel Review the original target was extracted and both the target and its vessel were inspected. • The Collaboration has cooperated with CERN in the evaluation of the inspection results reaching a common understanding of: the present status of the original target, the main reasons for the observed deficient status and the recorded abnormal behavior in 2004. • The explanation of the inspection results indicates that the original design requires improvements on: • Cooling (to insure acceptable temperature range all over the surface of the target but particularly in the beam hot spots) • Corrosion control and protection • Mechanical stability • Monitoring of target and cooling circuit

  9. After this understanding of the behavior of the previous target, the nTOF_Ph2 collaboration has maintained a close cooperation with CERN to identify and analyze the concepts for a new target. From December to last week there has been 4 fruitful meetings with intense exchange of analysis, experimental tests, computational simulations, concept proposals and cross checks particularly on the areas of thermal analysis, cooling circuit, water chemistry and corrosion control, stress and deformation analysis, and physics performance. These exchanges had allowed to clarify the details of the experimental requirements to the new target from the nTOF-Ph2 collaboration. We are convinced that the new target and associated facilities concepts discussed in those meetings, based on a lead target directly cooled by conditioned water and with additional corrosion protection, will reach the required improvements indicated before and, after final detail tuning, can provide a design that satisfies all the basic experimental requirements

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