Status of the n_TOF experiment

E.Chiaveri(EN-STI-EET)

On behalf of n_TOF collaboration

3/4 November 2011INTC Meeting

INTC Meeting

ITEMS Experimental campaign July – November 2011

EAR2 (experimental Area 2) follow up

Tentative planning for 2012

Summary

3/4 November 2011

INTC 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 2011

INTC Meeting

Measurements performed between July and November 2011

Reference measurements of the high energy (n,a) cross section of 10B with a CVD diamond detector for the prospect of future applications, CERN-INTC-2010-061 ; INTC-I-125Measurement of the neutron capture cross-section of 236U, CERN-INTC-2010-065 ; INTC-M-017The role of Fe and Ni for s-process nucleosynthesis in the early Universe and for innovative nuclear technologies ,CERN-INTC-2006-012 ; INTC-P-208.Neutron capture cross section measurements of 238U, 241Am and 243Am at n_TOF, CERN-INTC-2009-025 ; INTC-P-269.Measurement of the fission cross-section of 240Pu and 242Pu at CERN's n_TOF facility, CERN-INTC-2010-042 ; INTC-P-280.Irradiation of FBG optical sensors in the n_TOF dump, CERN-INTC-2011-031; INTC-I-135.MicroMegas performance test for (n,a) measurements at n_TOF: S33(n,a) cross section. CERN-INTC-2010-023 ; INTC-I-092Angular distributions in the neutron-induced fission of actinides, CERN-INTC-2010-038 ; INTC-P-209-ADD-1 3/4 November 2011

INTC Meeting

C. Weiss et al. (U. Wien), Reference measurements of the high energy (n,a) cross section of 10B with a CVD diamond detector for the prospect of future applications, CERN-INTC-2010-061

Neutrons

Detector (4 pads) box with Sample inside

Preamplifiers

Preamplifiers

n_TOF

γ –background?

!

pCVD developed and used for 1st time!! - Very well shielded from g-flash - Preliminary Pulse Shape Analysis - Preliminary data analysis

3/4 November 2011

Improvement 2012:1. Thinner Diamond(Less background)2. Under vacuum(Better discrimination)

INTC Meeting

N. Colonna et al., (INFN-Bari), Measurement of the neutron capture cross-section of 236U, CERN-INTC-2010-065 ; INTC-M-017

• 236U3O8 sample• 338 mg of 236U• 99.85% Enriched• U6 Dimensions: 10 x 0.25 mm• Al Canning dimensions: 15 x 0.75 mm• Composition: 0.05% U5 99.85 U6 0.10%

U8

3/4 November 2011

INTC Meeting

N. Colonna et al., (INFN-Bari), Measurement of the neutron capture cross-section of 236U, CERN-INTC-2010-065 ; INTC-M-017 [Measurement with C6D6]

3/4 November 2011

Full range in one shot!Optimal signal to background ratio!!

INTC Meeting

N. Colonna et al., (INFN-Bari), Measurement of the neutron capture cross-section of 236U, CERN-INTC-2010-065 ; 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 238U, 241Am and 243Am at n_TOF, CERN-INTC-2009-025 ; INTC-P-269.

• Wide sample, with perfect alignment it covers ~97% of the beam (53.90 x 30.30 mm) [NOT SEALED!!!]

• 6.125 ± 0.002 g• Isotopic analysis done in 1984: <1 ppm 233U, <1ppm 234U,

~11ppm 235U, <1ppm 236U• ‘Bonbon’ casing with ~60 microns of Al, ~75 microns

Kapton

NominalEAST TOF

238U

TOF EAST

3/4 November 2011

Nominal values: TOF~8E12 ppp / EAST~3e12ppp

Original 238U mass~600 mg

Final mass of 238U~6g :Counting rates up to 3-4

counts/microsecond

Since the TAC can hold only up to 1 counts/microsecond:

TOF intensity reduced to 0.5-0.9e12 ppp

INTC Meeting

D. Cano-Ott (CIEMAT, Madrid) and F. Gunsing (CEA, Saclay) et al., Neutron capture cross section measurements of 238U, 241Am and 243Am at n_TOF, CERN-INTC-2009-025 ; INTC-P-269.

3/4 November 2011

238UDummyEmpty

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 damage2. 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 l) 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 l)

3/4 November 2011INTC Meeting

INTC Meeting

240PuENDF/B-VII

235UENDF/B-VII

240,242Pu(n,f) with MGAS (A: Tsinganis)

242Pu (1.2MBq)

240Pu (27.3MBq)

3/4 November 2011

M. Calviani, (CERN), E. Berthoumieux (CEA, Saclay) et al., Measurement of the fission cross-section of 240Pu and 242Pu at CERN's n_TOF facility, CERN-INTC-2010-042 ; INTC-P-280.

INTC Meeting

J. Praena (U. Sevilla) and I. Porras (U. Granada) et al, MicroMegas performance test for (n,a) measurements at n_TOF: 33S(n,a) cross section. CERN-INTC-2010-023 ; INTC-I-092

[SCHEDULLED FOR 9-21 NOVEMBER 2011]

MGAS set-up (back-to-back samples to study

ang. distr.)

Empty 10B 33S(x2 thin) 33S(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 Cu2S, 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 2011

INTC Meeting

L. Tassan-Got (IN2P3, Orsay) et al., Angular distributions in the neutron-induced fission of actinides, CERN-INTC-2010-038 ; INTC-P-209-ADD-1 [SCHEDULLED 9-21 NOVEMBER]

Starts from succesful n_TOF-Ph1 meas. with PPAC (237Np & 209Bi 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 (235U, 238U, 237Np, 6x232Th)•Segmented cathodes to study the ang. distributions of FF, in addition to sn,f(En).

3/4 November 2011

INTC 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 photonsIf these tests are successful -> INTC proposal

3/4 November 2011

INTC Meeting

Overview of the n_TOF spallation target area

n_TOF target pit

Technical gallery (@10 m from pit)

EAR2 (@20 m from pit, above ground)Ex

isti

ng h

ole

To b

e bu

ilt

ISR

3/4 November 2011

INTC 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 2011

INTC Meeting

N_TOF measurements plan 2012

Measurement Detector # Prot. (e18)[proposal]

Dates Comments

Start Up Varii 0.5238U s(n,g) C6D6 3 Approved by INTC

88Sr (Spins and D0) TAC 2 If approved by INTC88Sr s(n,g) C6D6 2 If approved by INTC

235U s(n,g)/s(n,f) TAC+MGAS 4 If approved by INTC 93Zr 3 If approved by INTC

240,242Pu s(n,f) MGAS 3 In parallel231Pa,234U Ang. Distr. PPAC 2 To be proposed(n,a) with Diamond pCVD 4 To be proposed(n, a) with MGAS MGAS 2 To be proposed

Total 22.5

3/4 November 2011

INTC Meeting

Summary

2011 experimental campaign According to scheduled program

EAR-2 (Experimental Area 2) Final Conceptual Design Document on progress

Planning for experimental campaign 2012 88Sr Clarification letter 235U Fission Tagging of Proposal 93Zr Proposal

3/4 November 2011