n_tof-ph2 the physics case and the related proposal for measurements at n_tof for the period...

nn_TOF-Ph_TOF-Ph22The Physics case and the related proposal The Physics case and the related proposal for measurements at n_TOF for the period for measurements at n_TOF for the period 2006-20102006-2010

A MengoniA MengoniCERN , GenevaCERN , GenevaENEA, BolognaENEA, Bologna

The CERN The CERN nn_TOF Facility_TOF Facility n_TOF 1-2-3: the physics casesn_TOF 1-2-3: the physics cases Capture studies, fission studies and othersCapture studies, fission studies and others Opportunities with a new, shorter flight-path & EAR-2Opportunities with a new, shorter flight-path & EAR-2 Phase-2 implementationPhase-2 implementation

www.cern.ch/n_TOF

The The nn_TOF facility at CERN_TOF facility at CERN

www.cern.ch/n_TOF

TThe real worldhe real world nn_TOF commissioned_TOF commissioned

in 2002in 2002

www.cern.ch/n_TOF

nn_TOF basic parameters_TOF basic parametersproton 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 and resolutionand resolutionin the full energy in the full energy rangerange

2nd collimator =1.8 cm

nn_TOF _TOF TTAC for (n,AC for (n,) ) measurementsmeasurements

• High detection efficiency: ≈100% (to be compared with 5% of C6D6 or 0.1% of Moxon-Rae)

• Good energy resolution (direct background suppression mechanisms based on combined multiplicity and energy deposition analysis)

n

• 40 BaF2 crystals 12 pentagons & 28 hexagons 15 cm crystal thickness Carbon-fiber 10B-enriched capsules

• Full Monte Carlo simulations all EM cascades capture events for BG determination

The n_TOF Collaboration


• Structure mounted in April-04• 4 geometry: end of May-04• 1.5 month commissioning• Au(n,) & other standards

First measurement with a radioactivesample started in August 2004

237Np(n,)

www.cern.ch/n_TOF

sample

nn_TOF _TOF TTAC for (n,AC for (n,) ) measurementsmeasurements

WWhy we do all thishy we do all this??

Objectives of the activity at Objectives of the activity at nn_TOF_TOF

1.1. CCross sections relevant for Nuclear Astrophysicsross sections relevant for Nuclear Astrophysics

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

3.3. NNeutrons as probes for fundamental Nuclear Physicseutrons as probes for fundamental Nuclear Physics


(*) contract with the EC (FP5) ended on December 2004www.cern.ch/n_TOF

www.cern.ch/n_TOF

[email protected]

neutrons

56Fe 91.72

57Fe 2.2

58Fe 0.28

Fe

Co

60Ni 26.223

59Co100

59Fe 44.503 d

60Fe 1.5 106 a

60Co5.272 a

61Co1.65 h

61Ni 1.140

62Ni 3.634

Ni 63Ni 100 a

64Ni 0.926

58Co70.86 d

62Cu9.74 m

63Cu69.17

64Cu 12.7 h

61Fe 6 m

Cu

[email protected]

56Fe 91.72

57Fe 2.2

58Fe 0.28

Fe

Co

60Ni 26.223

59Co100

59Fe 44.503 d

60Fe 1.5 106 a

60Co5.272 a

61Co1.65 h

61Ni 1.140

62Ni 3.634

Ni 63Ni 100 a

64Ni 0.926

58Co70.86 d

62Cu9.74 m

63Cu69.17

64Cu 12.7 h

61Fe 6 m

Cu

[email protected]

The canonical s-process

½ of the elements above Fe are produced by the s-process½ of the elements above Fe are produced by the s-process The astrophysical sites of the s-process are:The astrophysical sites of the s-process are:

He burning in intermediate/massive starsHe burning in intermediate/massive stars Low-mass AGB’sLow-mass AGB’s

There exists a direct correlation There exists a direct correlation between the neutron capture cross section between the neutron capture cross section and the abundance (and the abundance ((n,(n,) ) ·· N = const. N = const.))

The neutron capture cross sections The neutron capture cross sections are key ingredients for s-process nucleosynthesisare key ingredients for s-process nucleosynthesis

NNucleosynthesis: the ucleosynthesis: the ss--process process

NNucleosynthesis: ucleosynthesis: the s-process &the s-process &the r-process residualsthe r-process residuals

NNrr = N= Nsolarsolar - N - NssNNrr = N= Nsolarsolar - N - Nss

20 40 60 80 100 120NEUTRON NUMBER

1

10

100

1000

MA

XW

EL

LIA

N A

VE

RA

GE

D C

RO

SS S

EC

TIO

N

(mb)

BaBa

CdCd

CeCe

CrCr

DyDy ErEr

FeFe

GdGd

GeGe

HfHf

HgHgKrKr

MoMo NdNdNiNi

OsOs

PbPb

PdPd

PtPt

RuRuSeSe

SmSm

SnSn

SrSr

TeTe

WW

XeXe

YbYbZnZn

ZrZr

even-even nuclei

Neutron capture cross Neutron capture cross sections:sections:available dataavailable data

Objectives of the activity at Objectives of the activity at nn_TOF_TOF


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



(*) contract with the EC (FP5) ended on December 2004www.cern.ch/n_TOF

NNuclear waste: TRU uclear waste: TRU (1000 MW (1000 MW LWR)LWR)

239Pu: 132 Kg/yr

237Np: 10.1 Kg/yr

241Am: 0.5 Kg/yr 243Am: 2.4 Kg/yr

244Cm 0.6 Kg/yr

LLFP

LLFP 52.2 Kg/yr

LWR 52 Units

Spent fuel800 t/y

Recovered U, Pu760 t/y

REPROCESSINGHLWHLW

MA: 1t FP: 39tP&T TECHNOLOGIESP&T TECHNOLOGIES

FINAL DISPOSAL(100 times reduced)

PPartitioning and artitioning and TTransmutationransmutation

Yucca Mountain repository would last for 500 Yucca Mountain repository would last for 500 yr !yr !

Nuclear Data needs for Nuclear Data needs for AADSDS Subcritical reactor coreSubcritical reactor core Spallation neutrons: high Spallation neutrons: high

energiesenergies Trasmutation of TRU: exotic fuelTrasmutation of TRU: exotic fuel

Zen-ADS

AcceleratorAcceleratorprotons

Reactor neutrons

www.cern.ch/n_TOF

nn_TOF experiments _TOF experiments 2002-42002-4


TTargetarget Motivations & NotesMotivations & Notes24,25,2624,25,26MgMg Isotopic abundance ratios in stellar grains. Isotopic abundance ratios in stellar grains.

Importance of Importance of 2222Ne(Ne(,n),n)2525Mg for the s-process Mg for the s-process neutron balance. neutron balance.

Light nuclei, small cross sections. Light nuclei, small cross sections.

90,91,92,93,94,9690,91,92,93,94,96ZrZr s-process branching at A=95 & observed abundance s-process branching at A=95 & observed abundance patterns in stellar grains. Sensitivity to neutron flux patterns in stellar grains. Sensitivity to neutron flux during the s-process.during the s-process.9393Zr(Zr(1/21/2 = 1.5 Myr) = 1.5 Myr)

139139LaLa Bottleneck in the s-process flow. N=82 neutron shell Bottleneck in the s-process flow. N=82 neutron shell closureclosure

151151SmSm s-process branching at A s-process branching at A ≈ 150. ≈ 150. 151151Sm is radioactive Sm is radioactive

((1/21/2 = 93 yr) = 93 yr)

186,187,188186,187,188OsOs Nuclear cosmochronology (Re/Os clock)Nuclear cosmochronology (Re/Os clock)

s-process branching at A s-process branching at A ≈ 185≈ 185

204,206,207,208204,206,207,208PbPb209209BiBi

Termination of the s-process. Small Termination of the s-process. Small //elel

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-Ph_TOF-Ph22 objectives objectives


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


The n_TOF Collaborationwww.cern.ch/n_TOF

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: ~ 100expected neutron flux enhancement: ~ 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: ~ 100expected neutron flux enhancement: ~ 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

Letter of IntentLetter of Intent signed by signed by 2424 research labs of the n_TOF Collaboration + research labs of the n_TOF Collaboration + 44

newcomersnewcomers(January 2005)(January 2005)

n_TOF-Phn_TOF-Ph22 scientific proposal scientific proposal the n_TOF 1-2-3 document (September 2004)the n_TOF 1-2-3 document (September 2004) CB meeting of February 10-11, 2005CB meeting of February 10-11, 2005 the the nn_BANT Symposium (March 2005)_BANT Symposium (March 2005) INTC meeting (May 2005) INTC meeting (May 2005) Joint n_TOF/ISOLDE initiative: NuPAC (Nuclear Physics and Joint n_TOF/ISOLDE initiative: NuPAC (Nuclear Physics and

Astrophysics at CERN)- “Villars meeting” @ CERN promoted by Astrophysics at CERN)- “Villars meeting” @ CERN promoted by the INTC (October 10-12, 2005)the INTC (October 10-12, 2005)

The n_TOF-Ph2 MoU – end of 2005/beginning of 2006The n_TOF-Ph2 MoU – end of 2005/beginning of 2006

Road-map towards n_TOF-PhRoad-map towards n_TOF-Ph22

www.cern.ch/n_TOF n_TOF-Ph2

: endorsement of the scientific case : endorsement of the scientific case for Ph2for Ph2

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 n_TOF-Ph2

n_TOF-Ph2

Capture studiesCapture studies

n_TOF-Ph2

Capture studies: Mo, Ru, and Pd Capture studies: Mo, Ru, and Pd

Motivations:Motivations:

• Accurate determination of the r-process Accurate determination of the r-process abundances (r-process residuals) from abundances (r-process residuals) from observationsobservations

• SiC grains carry direct information on s-process SiC grains carry direct information on s-process efficiencies in individual AGB stars. Abundance efficiencies in individual AGB stars. Abundance ratios in SiC grains strongly depend on available ratios in SiC grains strongly depend on available capture cross sections data.capture cross sections data.

Motivations:Motivations:

• Accurate determination of the r-process Accurate determination of the r-process abundances (r-process residuals) from abundances (r-process residuals) from observationsobservations

• SiC grains carry direct information on s-process SiC grains carry direct information on s-process efficiencies in individual AGB stars. Abundance efficiencies in individual AGB stars. Abundance ratios in SiC grains strongly depend on available ratios in SiC grains strongly depend on available capture cross sections data.capture cross sections data.

NNrr = N= Nsolarsolar - N - NssNNrr = N= Nsolarsolar - N - Nss

n_TOF-Ph2

• Setup: The n_TOF TACn_TOF TAC in EAR-1 (a few cases with C6D6 if larger neutron scattering)• All samples are stable and non-hazardous• Metal samples preferable (oxides acceptable)

Estimated # of protons 20 x 5x1016 = 10101818

sample

Capture studies: Mo, Ru, and Pd Capture studies: Mo, Ru, and Pd

n_TOF-Ph2

Capture studies: Fe, Ni, Zn & Capture studies: Fe, Ni, Zn & Se Se

Motivations: Motivations:

• Study of the weak s-process component (nucleosynthesis up to A ~ 90) • Contribution of massive stars (core He-burning Contribution of massive stars (core He-burning phase) to the s-process nucleosynthesis.phase) to the s-process nucleosynthesis.

• s-process efficiency due to bottleneck cross s-process efficiency due to bottleneck cross sections (Example: sections (Example: 6262Ni) Ni)

Motivations: Motivations:

• Study of the weak s-process component (nucleosynthesis up to A ~ 90) • Contribution of massive stars (core He-burning Contribution of massive stars (core He-burning phase) to the s-process nucleosynthesis.phase) to the s-process nucleosynthesis.

• s-process efficiency due to bottleneck cross s-process efficiency due to bottleneck cross sections (Example: sections (Example: 6262Ni) Ni)

In addition:In addition:

Fe and Ni are the most important structural materials for nuclear technologies. Fe and Ni are the most important structural materials for nuclear technologies. Results of previous measurements at n_TOF show that capture rates for light Results of previous measurements at n_TOF show that capture rates for light and intermediate-mass isotopes need to be revised.and intermediate-mass isotopes need to be revised.

In addition:In addition:

Fe and Ni are the most important structural materials for nuclear technologies. Fe and Ni are the most important structural materials for nuclear technologies. Results of previous measurements at n_TOF show that capture rates for light Results of previous measurements at n_TOF show that capture rates for light and intermediate-mass isotopes need to be revised.and intermediate-mass isotopes need to be revised.

n_TOF-Ph2

32

30

34

38 40 42 44 46 48 50

Capture studies: Fe, Ni, Zn & Capture studies: Fe, Ni, Zn & Se Se

The The 7979Se caseSe case

• s-process branching: neutron density & temperature s-process branching: neutron density & temperature conditions for the weak component.conditions for the weak component.• tt1/21/2 < 6.5 x 10 < 6.5 x 104 4 yryr

The The 7979Se caseSe case

• s-process branching: neutron density & temperature s-process branching: neutron density & temperature conditions for the weak component.conditions for the weak component.• tt1/21/2 < 6.5 x 10 < 6.5 x 104 4 yryr

• Setup: CC66DD66 in EAR-1• All samples are stable(*) and non-hazardous• Metal samples preferable (oxides acceptable)

Capture studies: Fe, Ni, Zn & Capture studies: Fe, Ni, Zn & SeSe

(*) except 79Se

n_TOF-Ph2

n_TOF-Ph2

Capture studies: A Capture studies: A ≈ 150≈ 150

• 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

• EAR-2 requiredEAR-2 required• Sample from ISOLDE?Sample from ISOLDE?• EAR-2 requiredEAR-2 required• Sample from ISOLDE?Sample from ISOLDE?

Capture studies: actinidesCapture studies: actinides

Neutron cross section measurements for nuclear waste Neutron cross section measurements for nuclear waste transmutation and advanced nuclear technologiestransmutation and advanced nuclear technologies

241,243241,243AmAm The most important neutron poison in the fuels proposed for transmutation scenarios. Build up of Cm isotopes.

239,240,242239,240,242PuPu (n,) and (n,f) with active canning. Build up of Am and Cm isotopes.

245245CmCm No data available.

235,238235,238UU Improvement of standard cross sections.

232232Th,Th,233,234233,234UU231,233231,233PaPa

Th/U advanced nuclear fuels. 233U fission with active canning.

All measurements can be done in EAR-1 (except All measurements can be done in EAR-1 (except 241241Am and Am and 233233Pa)Pa)All measurements can be done in EAR-1 (except All measurements can be done in EAR-1 (except 241241Am and Am and 233233Pa)Pa)

50m Kapton windows

400m ISO 2919 Ti canning (400 mg!) +

actinide sampleair

vacuum

Neutron absorber

Calorimeter

rays

Actual setup with thick sample cannings

Capture studies: actual TAC setupCapture studies: actual TAC setup

n_TOF-Ph2

C12H20O4(6Li)2

Neutron Absorber

10B loaded Carbon Fibre

Capsules

Neutron Beam

n_TOF-Ph2

Effect of the Ti canning (neutron sensitivity)

Capture studies: actual TAC setupCapture studies: actual TAC setup

Window surrounded by neutron absorber

(10B or 6Li doped polyethylene)

Thin Al backing +

actinide sample

vacuum

Neutron absorber

Calorimeter

Capture studies: Capture studies: Low neutron Low neutron sensitivity setupsensitivity setup

n_TOF-Ph2

Neutron beam

Mini Ionisation chamber

Stack of with 200 g/cm2

samples on thin backings

Fission Fragments

rays

Measurement of capture cross sections of fissile materials (veto) and measurement of the (n,)/(n,f) ratio.

Capture studies: Capture studies: active canning for active canning for simultaneous (n,simultaneous (n,) & (n,f) measurements) & (n,f) measurements

n_TOF-Ph2

<< back<< back

n_TOF-Ph2

Fission studiesFission studies

n_TOF-Ph2

45 degrees

p’

n

"Thin" E detector

E detector

235U

proton containing target (polyethylene)

fission fragmentsdetector

"Thick" E/Low E detector

104 105 106 107 108

1E-3

0.01

0.1

Count rate protons

235

U

Counts

En, eV

BeamBeam capture mode (2 mm capture mode (2 mm ØØ))

Scattering angleScattering angle 3030°°

Target thicknessTarget thickness 250 250 g/cmg/cm22

Detector radiusDetector radius 20 mm20 mm

Target-to-detector distanceTarget-to-detector distance 250 mm250 mm

Fission studies Fission studies absolute absolute 235235U(n,f) cross section from (n,p) U(n,f) cross section from (n,p) scatteringscattering

(n,p) larger or comparable up to 100 MeV

H235U 0.01 1 100 Neutron energy [MeV]

n_TOF-Ph2

Fission studies Fission studies FF distributions in vibrational resonancesFF distributions in vibrational resonances

Neutron beam

Position-sensitivedetector

Time-tag detector

Sample

Vacuum chamber

Principles:Principles:

• Time-tag detector for the “start” signal• Masses (kinetic energies) of FF from position-sensitive detectors (MICROMEGAS or semiconductors)

Principles:Principles:

• Time-tag detector for the “start” signal• Masses (kinetic energies) of FF from position-sensitive detectors (MICROMEGAS or semiconductors)

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n_TOF-Ph2

Fission studies Fission studies cross sections with PPAC detectors: present cross sections with PPAC detectors: present setup setup

Measurements:Measurements:

• 231231Pa(n,f) Pa(n,f) • Fission fragments angular distributions (45Fission fragments angular distributions (45°° tilted targets) tilted targets) for for 232232Th, Th, 238238U and other low-activity actinidesU and other low-activity actinides

EAR-EAR-22 boost: boost:• measurements of measurements of 241,243241,243Am (in class-A lab)Am (in class-A lab)• measurements of measurements of 241241Pu and Pu and 244244Cm (in class-A lab)Cm (in class-A lab)


• 231231Pa(n,f) Pa(n,f) • Fission fragments angular distributions (45Fission fragments angular distributions (45°° tilted targets) tilted targets) for for 232232Th, Th, 238238U and other low-activity actinidesU and other low-activity actinides

EAR-EAR-22 boost: boost:• measurements of measurements of 241,243241,243Am (in class-A lab)Am (in class-A lab)• measurements of measurements of 241241Pu and Pu and 244244Cm (in class-A lab)Cm (in class-A lab)

<< back<< back

n_TOF-Ph2

Fission studies Fission studies with twin ionization chamber with twin ionization chamber


• FF yields: mass & charge FF yields: mass & charge • Test measurement with Test measurement with 235235U then measurements of other MAU then measurements of other MA


• FF yields: mass & charge FF yields: mass & charge • Test measurement with Test measurement with 235235U then measurements of other MAU then measurements of other MA

Twin ionization detector with measurement ofboth FF (PPAC principle)

<< back<< 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


• 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

n_TOF-Ph2

Neutron scattering reactionsNeutron scattering reactions

N e u tro n b e a m

D ta rg e t2

P ro to n d e te c to r

N e u tro n d e te c to r

5 m

3 4 º

8 0 º

4 6 c

m

D 3

D 4

Neutron incident energy 30 – 75 MeV in 2.5 MeV bins

Kiematic locus of the n + 2H n + p + n reaction for:En = 50 MeVΘn = 20º, Φn = 0ºΘp = 50º, Φp = 180º

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Direct n + n scattering experiment not feasible! Direct n + n scattering experiment not feasible!

Alternatively, interaction of two neutrons in the final Alternatively, interaction of two neutrons in the final state of a nuclear reaction. Examples of such state of a nuclear reaction. Examples of such reactions are:reactions are:

++ + + 22H H n + n + n + n +

n + n + 22H H n + n + p n + n + p

n_TOF-Ph2

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n_tof-ph2 the physics case and the related proposal for measurements at n_tof for the period...

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