Status of the n_TOF experiment E.Chiaveri ( EN-STI-EET ) On behalf of n_TOF collaboration 3/4 November 2011INTC Meeting

ITEMS Experimental campaign July – November 2011 EAR2 (experimental Area 2) follow up Tentative planning for 2012 Summary 3/4 November 2011INTC Meeting

Proton status Thanks to the earlier start and to the higher intensity/pulse n_TOF reaches for the first time its intensity request/year 3/4 November 2011INTC Meeting

Measurements performed between July and November 2011 Reference measurements of the high energy (n,  ) cross section of 10 B with a CVD diamond detector for the prospect of future applications, CERN-INTC ; INTC-I- 125 Measurement of the neutron capture cross-section of 236 U, CERN-INTC ; INTC- M-017 The role of Fe and Ni for s-process nucleosynthesis in the early Universe and for innovative nuclear technologies,CERN-INTC ; INTC-P-208. Neutron capture cross section measurements of 238 U, 241 Am and 243 Am at n_TOF, CERN-INTC ; INTC-P-269. Measurement of the fission cross-section of 240 Pu and 242 Pu at CERN's n_TOF facility, CERN-INTC ; INTC-P-280. Irradiation of FBG optical sensors in the n_TOF dump, CERN-INTC ; INTC-I-135. MicroMegas performance test for (n,a) measurements at n_TOF: S33(n,a) cross section. CERN-INTC ; INTC-I-092 Angular distributions in the neutron-induced fission of actinides, CERN-INTC ; INTC-P-209-ADD-1 3/4 November 2011INTC Meeting

C. Weiss et al. (U. Wien), Reference measurements of the high energy (n,  ) cross section of 10 B with a CVD diamond detector for the prospect of future applications, CERN-INTC Neutrons Detector (4 pads) box with Sample inside Preamplifiers n_TOF γ –background?! pCVD developed and used for 1st time!! - Very well shielded from  -flash - Preliminary Pulse Shape Analysis - Preliminary data analysis 3/4 November 2011INTC Meeting Improvement 2012: 1.Thinner Diamond (Less background) 2.Under vacuum (Better discrimination)

N. Colonna et al., (INFN-Bari), Measurement of the neutron capture cross-section of 236 U, CERN-INTC ; INTC-M U 3 O 8 sample 338 mg of 236 U 99.85% Enriched U6 Dimensions: 10 x 0.25 mm Al Canning dimensions: 15 x 0.75 mm Composition:0.05% U U6 0.10% U8 3/4 November 2011INTC Meeting

N. Colonna et al., (INFN-Bari), Measurement of the neutron capture cross-section of 236 U, CERN-INTC ; INTC-M-017 [Measurement with C6D6] 3/4 November 2011INTC Meeting Full range in one shot! Optimal signal to background ratio!!

N. Colonna et al., (INFN-Bari), Measurement of the neutron capture cross-section of 236 U, CERN-INTC ; INTC-M-017 [Measurement with the TAC] Empty RRR limit in ENDF 3/4 November 2011 INTC Meeting

D. Cano-Ott (CIEMAT, Madrid) and F. Gunsing (CEA, Saclay) et al., Neutron capture cross section measurements of 238 U, 241 Am and 243 Am at n_TOF, CERN-INTC ; INTC-P-269. Wide sample, with perfect alignment it covers ~97% of the beam (53.90 x mm) [NOT SEALED!!!] ± g Isotopic analysis done in 1984: <1 ppm 233 U, <1ppm 234 U, ~11ppm 235 U, <1ppm 236 U ‘Bonbon’ casing with ~60 microns of Al, ~75 microns Kapton Nominal EAST TOF 238 U TOF EAST 3/4 November 2011INTC Meeting Nominal values: TOF~8E12 ppp / EAST~3e12ppp Original 238 U mass~600 mg Final mass of 238 U~6g : Counting rates up to 3-4 counts/microsecond Since the TAC can hold only up to 1 counts/microsecond: TOF intensity reduced to e12 ppp

D. Cano-Ott (CIEMAT, Madrid) and F. Gunsing (CEA, Saclay) et al., Neutron capture cross section measurements of 238 U, 241 Am and 243 Am at n_TOF, CERN-INTC ; INTC-P /4 November 2011INTC Meeting 238 U Dummy Empty First Resonance Third Resonance Second Resonance

PARASITIC MEASUREMENT NEAR THE N_TOF BEAM DUMP: 1.FBG in vacuum: sensitive to sudden and continuous changes in temperature and material damage 2.Fibers in air sensitive to material damage. If effects are NOT observed: green light for the use of fibers in high neutron field environments. If effects ARE observed: possibility to use FBG as neutron dosimeters, neutron profilers, etc. Experimental results for two FBG under the proton beam exposure with polyimide coating (coated) and embedded in a fiber composite material (embedded). Black line shows the ambient temperature wavelength shifts in the reference FBG (off beam). R. Palomo, J.M. Quesada and C. Guerrero, Use of FBG sensors as temperature-based Beam Profile Monitors Optical Fibers with Bragg Gratings (100% transmission except for the selected ) are used for measuring temperature changes, deformations and recently dose induced by protons. Neutron interactions may induce measurable effects in Fiber Bragg Gratings (already observed in protons beams) by means of (among others): Nucleus recoils inducing changes in temperature Material damage Nuclear reactions that would change the composition of the fiber (thus the transmitted ) 3/4 November 2011INTC Meeting

240 Pu ENDF/B-VII 235 U ENDF/B-VII 240,242 Pu(n,f) with MGAS (A: Tsinganis) 242 Pu (1.2MBq) 240 Pu (27.3MBq) 3/4 November 2011INTC Meeting M. Calviani, (CERN), E. Berthoumieux (CEA, Saclay) et al., Measurement of the fission cross- section of 240 Pu and 242 Pu at CERN's n_TOF facility, CERN-INTC ; INTC-P-280.

J. Praena (U. Sevilla) and I. Porras (U. Granada) et al, MicroMegas performance test for (n,a) measurements at n_TOF: 33 S(n,a) cross section. CERN-INTC ; INTC-I-092 [SCHEDULLED FOR 9-21 NOVEMBER 2011] MGAS set-up (back-to-back samples to study ang. distr.) Empty 10 B 33 S(x2 thin) 33 S(x2 thick) Sample preparation at CERN: The solution has been found by reacting S while being evaporated with a thin Cu layer deposited onto a thin Kapton foil, to form a stable compound Cu 2 S, which is strongly adherent to the substrate. Sample characterization at CNA: Surface density and homogeneity determined at CNA (Seville) via RBS using protons and alphas. 3/4 November 2011INTC Meeting

L. Tassan-Got (IN2P3, Orsay) et al., Angular distributions in the neutron-induced fission of actinides, CERN-INTC ; INTC-P-209-ADD-1 [SCHEDULLED 9-21 NOVEMBER] Starts from succesful n_TOF-Ph1 meas. with PPAC ( 237 Np & 209 Bi up t 1 GeV among others) Limited ang. acceptance Signficant corrections due to uncertain ang.distributions n_TOF Ph-2 set-up: Samples tilted 45degrees wrt. neutron beam 10 PPAC detectors with 9 targets in between ( 235 U, 238 U, 237 Np, 6x 232 Th) Segmented cathodes to study the ang. distributions of FF, in addition to  n,f (E n ). 3/4 November 2011INTC Meeting

Detector tests to prepare forthcoming years  Proton telescope to measure (n,p) (n,d) reaction up to 1 GeV (Dubna, Kyushu)  Detector behavior with respect to the gamma-flash: 1GeV -> TOF~90 ns, 500 MeV -> TOF~200 ns  Detector timing performance  Silicon strip for (n,p) (n,a) of astrophysics interest (University of Edinburgh)  Detector behavior in the vicinity of the neutron beam  Combination of high granularity detectors with TOF measurements  Test of BGO and CVD Diamond detector  Investigation of the response to high energy photons If these tests are successful -> INTC proposal 3/4 November 2011INTC Meeting

Overview of the n_TOF spallation target area n_TOF target pit Technical gallery m from pit) EAR2 m from pit, above ground) Existing hole To be built ISR 3/4 November 2011INTC Meeting

EAR-2 Experiments follow-up  Final Conceptual Design Document will be presented and discussed to Collaboration Board (Dec 2011)  February 2012 will be presented to INTC  End of February will be presented to Research Board for the final approval 3/4 November 2011INTC Meeting

N_TOF measurements plan 2012 MeasurementDetector# Prot. (e18) [proposal] DatesComments Start Up Varii U  (n,  ) C6D63 Approved by INTC 88 Sr (Spins and D 0 )TAC2 If approved by INTC 88 Sr  (n,  ) C6D62 If approved by INTC 235 U  (n,  )/  (n,f) TAC+MGAS4 If approved by INTC 93 Zr3 If approved by INTC 240,242 Pu  (n,f) MGAS3 In parallel 231 Pa, 234 U Ang. Distr.PPAC2 To be proposed (n,  ) with Diamond pCVD4 To be proposed (n,  ) with MGAS MGAS2 To be proposed Total22.5 3/4 November 2011INTC Meeting

Summary 2011 experimental campaign According to scheduled program EAR-2 (Experimental Area 2) Final Conceptual Design Document on progress Planning for experimental campaign Sr Clarification letter 235 U Fission Tagging of Proposal 93 Zr Proposal 3/4 November 2011INTC Meeting