the n _tof facility at cern

The The nn_TOF facility at CERN_TOF facility at CERN

somewhere around here

www.cern.ch/n_TOF

CERN accelerator CERN accelerator CComplexomplex

n_TOF

Linac(s): up to 50 MeV PSB: up to 1 GeV PS: up to 24 GeVLinac(s): up to 50 MeV PSB: up to 1 GeV PS: up to 24 GeVwww.cern.ch/n_TOF

The The nn_TOF facility at CERN_TOF facility at CERN

www.cern.ch/n_TOF

44

nn_TOF_TOF nn_TOF commissioned_TOF commissioned

in 2002in 2002

www.cern.ch/n_TOF

sample

June 2004

nn_TOF basic parameters_TOF basic parameters

[email protected]

proton beam momentumproton beam momentum 20 GeV/c20 GeV/c

intensity intensity (dedicated mode)(dedicated mode) 7 x 107 x 1012 12 protons/pulseprotons/pulse

repetition frequencyrepetition frequency 1 pulse/2.4s1 pulse/2.4s

pulse widthpulse width 6 ns (rms)6 ns (rms)

n/pn/p 300300

lead target dimensionslead target dimensions 80x80x60 cm80x80x60 cm33

cooling & moderation materialcooling & moderation material HH22OO

moderator thickness in the exit moderator thickness in the exit faceface

5 cm5 cm

neutron beam dimension in EAR-1neutron beam dimension in EAR-1

(capture mode)(capture mode)2 cm (FWHM)2 cm (FWHM)

TThe real worldhe real world nn_TOF beam _TOF beam

characteristics: characteristics: Neutron intensity Neutron intensity in the full energy in the full energy rangerange

2nd collimator =1.8 cm

TThe real worldhe real world

[email protected]

TAC 237Np(n,) 2004 measurement

www.cern.ch/n_TOF

nn_TOF beam _TOF beam characteristics: characteristics: energy resolutionenergy resolution

nn_TOF experiments _TOF experiments 2002-42002-4

CCaptureapture151151SmSm204,206,207,208204,206,207,208PbPb, , 209209BiBi

232232ThTh

24,25,2624,25,26MgMg

90,91,92,94,9690,91,92,94,96Zr, Zr, 9393ZrZr139139LaLa

186,187,188186,187,188OsOs

233,234233,234UU

237237NpNp,,240240PuPu,,243243AmAm

FFissionission233,234,235,236,238233,234,235,236,238UU

232232ThTh

209209BiBi237237NpNp

241,243241,243Am, Am, 245245CmCm

The n_TOF Collaboration

1.1. CCross sections relevant for ross sections relevant for Nuclear AstrophysicsNuclear Astrophysics

2.2. MMeasurements of neutron cross easurements of neutron cross sections relevant for Nuclear sections relevant for Nuclear Waste Transmutation and related Waste Transmutation and related Nuclear TechnologiesNuclear Technologies

3.3. NNeutrons as probes for eutrons as probes for fundamental Nuclear Physicsfundamental Nuclear Physics

The The nn_TOF-Ph_TOF-Ph22 experiments experiments

Capture measurementsCapture measurementsMo, Ru, Pd stable isotopes

Fe, Ni, Zn, and Se (stable isotopes)79Se

A≈150 (isotopes varii)

234,236U, 231,233Pa

235,238U

239,240,242Pu, 241,243Am, 245Cm

r-process residuals calculationisotopic patterns in SiC grains

s-process nucleosynthesis in massive starsaccurate nuclear data needs for structural materials

s-process branching pointslong-lived fission products

Th/U nuclear fuel cycle

standards, conventional U/Pu fuel cycle

incineration of minor actinides

n_TOF-Ph2

Fission measurementsFission measurementsMA

235U(n,f) with p(n,p’)

234U(n,f)

ADS, high-burnup, GEN-IV reactors

new 235U(n,f) cross section standard

study of vibrational resonances at the fission barrier

Other measurementsOther measurements147Sm(n,), 67Zn(n,), 99Ru(n,)58Ni(n,p), other (n,lcp)

Al, V, Cr, Zr, Th, 238U(n,lcp)

He, Ne, Ar, Xe

n+D2

p-process studiesgas production in structural materials

structural and fuel material for ADS and other advanced nuclear reactors

low-energy nuclear recoils (development of gas detectors)

neutron-neutron scattering length

n_TOF-Ph2

The The nn_TOF-Ph_TOF-Ph22 experiments experiments

n_TOF-Ph2

n_TOF targetn_TOF target

NewExperimentalArea (EAR-2)

The second n_TOF beam line & The second n_TOF beam line & EAR-2EAR-2

EAR-1 (at 185 m)

~ 20 m~ 20 m

Flight-path length : Flight-path length : ~~20 m20 mat 90at 90° respect to p-beam direction° respect to p-beam directionexpected neutron flux enhancement: 20 - 100expected neutron flux enhancement: 20 - 100drastic reduction of the tdrastic reduction of the t00 flash flash

Flight-path length : Flight-path length : ~~20 m20 mat 90at 90° respect to p-beam direction° respect to p-beam directionexpected neutron flux enhancement: 20 - 100expected neutron flux enhancement: 20 - 100drastic reduction of the tdrastic reduction of the t00 flash flash

Improvements (ex: Improvements (ex: 151151Sm case)Sm case)

sample mass / 3 sample mass / 3 s/bkgd=1s/bkgd=1 use BaFuse BaF22 TAC TAC x 10 x 10 use Duse D22OO 3030 x 5 x 5 use 20 m flight pathuse 20 m flight path 3030 x 100 x 100

consequences for consequences for sample masssample mass

50 mg50 mg

5 mg 5 mg 1 mg1 mg 10 10 gg

boosts sensitivity by a factor of 5000 !

problems of sample production and safety issues relaxed

EAR-EAR-22: Optimized sensitivity: Optimized sensitivity

The The nn_TOF Collaboration_TOF Collaboration

40 Research Institutions40 Research Institutions120 researchers 120 researchers www.cern.ch/n_TOF

The The EEndnd

www.cern.ch/n_TOF

[email protected]

RResultsesults

CCaptureapture151151SmSm204,206,207,208204,206,207,208Pb, Pb, 209209BiBi232232ThTh24,25,2624,25,26MgMg90,91,92,94,9690,91,92,94,96Zr, Zr, 9393ZrZr139139LaLa186,187,188186,187,188OsOs233,234233,234UU237237Np,Np,240240Pu,Pu,243243AmAm

FFissionission233,234,235,236,238233,234,235,236,238UU232232ThTh209209BiBi237237NpNp241,243241,243Am, Am, 245245CmCm

nn_TOF experiments_TOF experimentsU Abbondanno et al. - The n_TOF Collaboration

Phys. Rev. Lett. 93 (2004), 161103

• branching isotope in the Sm-Eu-Gd region: test for low-mass TP-AGB

• branching ratio (capture/-decay) provides infos on the thermodynamical conditions of the s-processing (if accurateaccurate capture rates are known!)

Sm

Eu

Gd

150Sm

151Sm 93 a

152Sm

153Sm 42.27 h

154Sm

151Eu

152Eu 9 h

153Eu

154Eu 8.8 a

155Eu 4.761 a

156Eu 15.2 d

152Gd

153Gd

239.47 d

154Gd

155Gd

156Gd

157Gd




n_TOF experimentsn_TOF experimentsU Abbondanno et al. - The n_TOF Collaboration

NIM A 521 (2004) 454

• 206 mg of 151SmO3

• encapsulated in 0.1 mm Ti• 200 GBq (5.3 Ci) activity

PHWT:accuracy better than 2%

(MC simulations of WF validated by measurements of resonances in 56Fe & others)



n_TOF experimentsn_TOF experiments

Very low background in capture cross sectionVery low background in capture cross sectionmeasurements on radioactive targetsmeasurements on radioactive targets

U Abbondanno et al. - The n_TOF CollaborationPhys. Rev. Lett. 93 (2004), 161103



nn_TOF experiments_TOF experimentsU Abbondanno et al. - The n_TOF Collaboration

Phys. Rev. Lett. 93 (2004), 161103

MACS-30 = 3100 ± 160 mbMACS-30 = 3100 ± 160 mb

<D0> = 1.48 ± 0.04 eV, S0 = (3.87 ± 0.20)×10-4

MACS-30 = 3100 ± 160 mbMACS-30 = 3100 ± 160 mb

<D0> = 1.48 ± 0.04 eV, S0 = (3.87 ± 0.20)×10-4

n_TOF


Main uncertainty components:- 3% flux normalization- 2% detector’s WF- 3% BG subtraction



IImplications mplications

Using the “classical” s-process model we obtain T8 > 4incompatible with realistic He-shell burning conditions

95% of neutrons are producedby 13C(,n) at kT ~ 8 keV. Underthese conditions, 152Gd cannotbe produced

During the He-burning episodethe 22Ne(,n) is activated atkT ~ 23 keV. The 151Sm -decay is fast enough to produce 70% of observed 152Gd (solar)

Present main uncertainties:• (T) of 151Sm• stellar capture rate

Inverse reactions



nn_TOF experiments_TOF experiments

Very low neutron sensitivity of capture Very low neutron sensitivity of capture -ray-raydetection systems & high resolutiondetection systems & high resolution

C Domingo-Pardo, et al. - The n_TOF CollaborationND2004 Conference, Santa Fe, NM – Sept. 2004207Pb(n,)






C Domingo-Pardo, et al. - The n_TOF CollaborationND2004 Conference, Santa Fe, NM – Sept. 2004209Bi(n,)





Low PS duty-cycle favours meaasurementsLow PS duty-cycle favours meaasurementson radiactive sampleson radiactive samples

F Gunsing, et al. - The n_TOF CollaborationND2004 Conference, Santa Fe, NM – Sept. 2004

232Th(n,)






F Gunsing, et al. - The n_TOF CollaborationND2004 Conference, Santa Fe, NM – Sept. 2004

232Th(n,)




nn_TOF experiments_TOF experimentsL Marques, et al. - The n_TOF Collaboration






L Marques, et al. - The n_TOF Collaboration





The extracted resonance parameters were compared witha previous measurement (Boldeman et al., 1976)

L Marques, et al. - The n_TOF Collaboration



nn_TOF experiments_TOF experimentsC Moreau, et al. - The n_TOF Collaboration

ND2004 Conference, Santa Fe, NM – Sept. 2004


≈≈ 20% lower20% lowerthan previous than previous

datadata

The extracted resonance parameters were compared withprevious measurements (Boldeman et al., 1976; Others)





93Zr(n,): raw data from 2004 measurement 10 mm


(n,(n,) x-section of ) x-section of 139139LaLa

[email protected]






139139LaLa

• Neutron magic N=82• mostly produced by the s-process• small x-section (resonance dominated) bottleneck in the s-process flow• accurate abbundance measurements exist can be used for normalization of s-process abundance





139La(n,) R Terlizzi, et al. (INFN)





Remarkable energy resolution and background conditions Remarkable energy resolution and background conditions have allowed to determine the resonance parameters up to 9 keVhave allowed to determine the resonance parameters up to 9 keVIn the past, the best experimental data did not exceed 2.7 keV.In the past, the best experimental data did not exceed 2.7 keV.

R Terlizzi et al. (INFN)


Up to 2.7 KeV:Up to 2.7 KeV:<capture strength> <capture strength> n_TOFn_TOF < 10% of Nakajima + Musgrove< 10% of Nakajima + Musgrove

< 20% of databases< 20% of databases

MACS-30 in agreement with the FZK activation measurement(s)MACS-30 in agreement with the FZK activation measurement(s)

139La(n,)



nn_TOF experiments_TOF experiments139La(n,) R Terlizzi et al. (INFN)


• The measurement at n_TOF confirmed the MACS-30 of the FZK The measurement at n_TOF confirmed the MACS-30 of the FZK activation measurement (O’Brien et al., PRC 68 (2003) 35801)activation measurement (O’Brien et al., PRC 68 (2003) 35801)

• With the new MACS, the With the new MACS, the ss-process contribution to the La -process contribution to the La production in TP-AGB is 73% (with respect to solar)production in TP-AGB is 73% (with respect to solar)

• A combined analysis with the Eu abundance (mostly A combined analysis with the Eu abundance (mostly rr) may furnish ) may furnish evidence on the origin and nature of the evidence on the origin and nature of the s-s- and and r-r- productions productions




• Long Long -decay half-life of -decay half-life of 187187ReRe

• s-only s-only 186186Os and Os and 187187OsOs



nn_TOF experiments_TOF experimentsM Mosconi, et al. – (The n_TOF Collaboration)ND2004 Conference, Santa Fe, NM – Sept. 2004




Theory still needed!Theory still needed!

For example, in 187Os at kT = 30 keV it is:

P(gs) = 33%P(1st) = 47%P(all others) = 20%




Age: Re/Os and Th/U clocks Age: Re/Os and Th/U clocks complementary

8.5 10.5




nn_TOF TAC in operation_TOF TAC in operation


233U(n,) W Dridi, E Berthoumieux, et al., (Dec. 2004)





W Dridi, E Berthoumieux, et al., (Dec. 2004)


234U(n,)

1.) Room + target frame background2.) Background due to the Ti canning +1.)3.) Activity4.) 234U + 2.) + 3.)





D Cano-Ott, et al. - The n_TOF CollaborationND2004 Conference, Santa Fe, NM – Sept. 2004




nn_TOF experiments_TOF experimentsD Cano-Ott, et al. - The n_TOF Collaboration






nn_TOF experiments_TOF experimentsD Cano-Ott, et al. - The n_TOF Collaboration


1% of statistics






1 10 100 1000 10000 100000 1000000 1E7 1E80.00.10.20.3

1

10

n_TOF James Lestone ENDF-B/VI

f, b

arns

En, eV

An unprecedent wide energy range can be An unprecedent wide energy range can be explored at n_TOF in a single experimentexplored at n_TOF in a single experiment

234U(n,f)


PPACs & FIC-0 (2003)




480 500 520 540 560 580 600 6200

1

2

3

4

5

6

234U(n,f)

FIS

SIO

N X

-SE

CTI

ON

, bar

b. u

.

NEUTRON ENERGY, eV

ORNL' 1977

480 500 520 540 560 580 600 620

0

200

400

600

800

1000

1200CERN' 2003

234U(n,f)

High-resolution data up to highHigh-resolution data up to high(er) energies(er) energies The n_TOF Collaboration

PPACs & FIC-0 (2003)





235U(n,f)


FIC-0 (2003)





1150 1200 1250 1300 1350 14000

300

600

900

CERN 2003

FIS

SIO

N C

RO

SS

-SE

CT

ION

, mb

NEUTRON ENERGY, eV

1150 1200 1250 1300 1350 14000

30

60

90

120

150

POMMARD236U(n,f)


FIC-1 (2003)





232Th(n,f)


PPAC detectors




High-resolution data up to highHigh-resolution data up to high(er) energies(er) energies

237Np(n,f)


FIC-0 (2003)




High-resolution data up to highHigh-resolution data up to high(er) energies(er) energies

245Cm(n,f)


FIC-1 (2003)


back

Validation & accuracy of Validation & accuracy of PHWTPHWT

Validation & accuracy of Validation & accuracy of PHWTPHWT

back

n_TOF-Ph2

1.1. CIC: compensated ion chamber CIC: compensated ion chamber already tested at n_TOFalready tested at n_TOF

For n_TOF-Ph2:

• four chambers in the same volume for multi-sample measurements

Measurements:Measurements:

• 147147Sm(n,Sm(n,) (tune up experiment)) (tune up experiment)• 66LiF target for calibrationLiF target for calibration

EAR-EAR-22 boost: boost:• approx 100 times the ORELA count rate approx 100 times the ORELA count rate expectedexpected• 6767Zn and Zn and 9999Ru (n,Ru (n,) measurements) measurements


• 147147Sm(n,Sm(n,) (tune up experiment)) (tune up experiment)• 66LiF target for calibrationLiF target for calibration

EAR-EAR-22 boost: boost:• approx 100 times the ORELA count rate approx 100 times the ORELA count rate expectedexpected• 6767Zn and Zn and 9999Ru (n,Ru (n,) measurements) measurements

(n,p), (n,(n,p), (n,) & (n,lcp) ) & (n,lcp) measurementsmeasurements

n_TOF-Ph2

2.2. MICROMEGAS MICROMEGAS already used for measurements of nuclear recoils at n_TOFalready used for measurements of nuclear recoils at n_TOF

For n_TOF-Ph2:

• converter replaced by sample

• expected count rate: 1 reaction/pulse (=200 mb, Ø=5cm, 1m thick)


<< back<< back

n_TOF-Ph2


3.3. Scattering chambers with Scattering chambers with E-E or E-E or E-E-E-E telescopes E-E telescopes


• 5656Fe and Fe and 208208Pb (tune up experiment)Pb (tune up experiment)• Al, V, Cr, Zr, Th, and Al, V, Cr, Zr, Th, and 238238UU• a few x 10a few x 1018 18 protons/sample in fission modeprotons/sample in fission mode


• 5656Fe and Fe and 208208Pb (tune up experiment)Pb (tune up experiment)• Al, V, Cr, Zr, Th, and Al, V, Cr, Zr, Th, and 238238UU• a few x 10a few x 1018 18 protons/sample in fission modeprotons/sample in fission mode

Setup: in parallel with fission detectors

production cross sections (En) for (n,xc)

c = p, , d

differential cross sections d/d, d/dE<< back<< back

Go Back

nn_TOF experiments_TOF experimentsL Marques, et al. - The n_TOF Collaboration

December 2004 2004


the n _tof facility at cern

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