Shvetsov iren report_sc_september_2008

September 25-26, 2008 JINR Scientific Council 104-th session

IREN First Stage IREN First Stage Project StatusProject Status


IREN project statusIREN project status• All equipment from electron gun down to experimental prototype

target assembled and tested;

• Regular nonmultiplying target is under manufacturing;

• Target hall repaired and ready for equipment assembling;

• Beam line #3 is equipped for the first experiments on 12 m, 30m, and 60 m flight passes;

• Accelerator testing have been started on June 17 – electron beam from the gun was obtained with designed parameters;

• At present time electron beam was transported through 1-st accelerating section in drift mode;

• Since September 15 2008 training of the RF power equipment started;

Test experiment at the IREN 1-st stage Test experiment at the IREN 1-st stage will be performed by the end of 2008will be performed by the end of 2008







Electron gun testingElectron gun testing

E-gun control room

Start pulse adjustments at IREN main control room



Start pulse

Ug = 170 kV (yellow channel); Jg = 5.6 А (blue channel); F = 50 Hz, Tp = 0,6 mks.

High voltage and electron current at e-gun



First electrons at IREN (beam trace at First electrons at IREN (beam trace at first diagnostics box after electron first diagnostics box after electron gun) June 17 2008gun) June 17 2008


Gamma quanta yield Gamma quanta yield

IREN 1-st stage – intensive source of bremsstrahlung gamma-quanta with energies up to the electron energy. Total intensity up to 1015 gammas/s.

Powerful tool for studying (,n), (,p) reactions.


IREN first stage calculated neutron IREN first stage calculated neutron spectraspectra


IREN first stage energy resolutionIREN first stage energy resolution

IREN 1-st stage pulse width for IREN 1-st stage pulse width for different neutron energies.different neutron energies.

IREN 1-st stage energy resolution IREN 1-st stage energy resolution at 10mat 10m


Neutron intensities at sample Neutron intensities at sample positionposition

Pulse neutron flux densities (n/cm2 sec) at 10 m flight path in different energy regions

• 0,5-10 eV 1,30*107 1,85*103

• 10-100 eV 5,26*107 4,38*102

• 100-1000 eV 1,78*108 1,48*102

• 1-10 keV 6,13*108 17,0• 10-100 keV 2,63*109 3,36

Count rate of 100 cm2 detector with 10% efficiency counts/s/eV


Experimental program for the Experimental program for the first stage of IRENfirst stage of IREN

• First experiment at IREN-1:– measurement of capture cross section for 181Ta:

demonstration experiment• Experimental program:

– cross section measurements for nuclear engineering and nuclear astrophysics;

– (n,p), (n, ) reactions;– nuclear structure studies: search for vibrational

resonances in stable nuclei;– search for subthreshold p-resonance in Pb;– neutron activation analysis– isotope production


30 40 50 60 70 80 90 100

10-1

100

101

102

103

104

105

Energy, eV

Co

un

ts IBR-30 (experiment) Iren (simulation)

Measurement of capture cross section for Measurement of capture cross section for 181181Ta: Ta: demonstration experimentdemonstration experiment

• 6 section liquid scintillator detector

• Placed at 60 m flight path

• Fully operational

Experimental spectrum of Experimental spectrum of 181181Ta Ta (n,(n,) at IBR-30 and simulated for ) at IBR-30 and simulated for 60m flight path at IREN60m flight path at IREN


(n,p), (n,) reactions

Nuclear astrophysics:

The Need for New (n, ), (n, ), and (n, p) Measurements

New Observations abundance measurements in stars isotopic anomalies in stardust and meteorites -ray astronomy

To test and improve astrophysical models New Astrophysical Models AGB stars (lower temperatures) supernovae

New Application for Neutron Data (n, ) measurements to improve reaction rates for explosive nucleosynthesis models; best means for constraining -particle reaction rates for models of supernovae, p-process and massive stars.

non-statistical effects in the -channel of neutron resonances:

”anomalous” resonances of 147Sm: 184, 385.16, 439.5, 667.0 eV) with alpha widths 7-14 larger than the average;

Integral distributions of the alpha widths;

reduced neutron widths are distributed according to the statistical theory;

for resonances with J=4- at Еn > 300 eV average value of the alpha width is 3 times larger than for those with J=3-.

experimental investigation of 35Cl(n,p)35S reaction is important for the study of interference efects of s- and p- resonances in the (n,p) reaction

Nuclear physics:


IREN facility short term perspectivesIREN facility short term perspectives

IREN 1-st stage calculated spectra for for 50 Hz frequency

and W target

IREN 1-st stage calculated spectra

for 150 Hz frequency and U target

Increasing pulse repetition rate up to designed value 150 Increasing pulse repetition rate up to designed value 150 Hz and replacement of the W target with U one will give Hz and replacement of the W target with U one will give

almost one order gain in neutron intensity. almost one order gain in neutron intensity.


ConclusionConclusion• In spite of relatively low intensity, IREN first stage, due to short

pulse, is giving us possibility to make certain experiments in high

neutron energy range.

• Significant gamma rays intensity in wide energy region (10 – 100

MeV) makes realistic extensive program of applied research.

• FLNP Directorate and project management thanks JINR Directorate,

Scientific Council and Committee of Plenipotentiaries for project

support.

• Test experiment at IREN 1-st stage will be performed by the end of

2008

Photos presented in report are made by Yu.Tumanov, P.Kolesov and V.Shvetsov

Science

Shvetsov iren report_sc_september_2008