İsmail Boztosun

Photofission of 238-U Nuclei

This research has been supported by TÜBİTAK with grant number 114F220

International Thorium Energy Conference - ThEC18,

29-31st of October 2018, Belgium

Motivations

i. Personal: From Theory to Experiment

ii. No dedicated research accelerators in developing world: Use of medical Linacs

- Advantages of having Good total photon flux

i. Fundamental Nuclear Science

ii. Aplication of Nuclear Tecniques

iii. Tranining & education facility for the PhD and MSc students

OUTLINE

• A New Landscape for developing countries,

• Nuclear Reactions & structure

• Proton Rich Nuclei and PR and GDR

measurements

• Photonuclear and Photofission Reactions,

• Experimental setup

• Electron Linac

• Detectors

• Results

• Summary & Outlook

• NUBA

Stable nuclei less than 300 !

~2000 KNOWN NUCLEI

Limits of existence

mass, charge & ratio N/Z

spin & temperature

extremes shapes

pro

tons

neutrons

The nucleus : a laboratory for

fundamental interactions and symmetries

Shell structure and Isospin

Spin and shapes

82

50

28

28

50

82

20

8 2

2

8

20

126

Key nuclei for

stellar processes are far

from stability

A landscape for Nuclear Reseach at Developing Countries with Medical Linacs

• High energies - Current Accelerators • Still interesting research for low energy charged particle and photon reactions

PHOTONUCLEAR REACTIONS

A B

target

projectile

B + b

product

ejectile

a

b

h • n

delayed

Target nuclide

“Compound nucleus”

Product nuclide

level

Prompt Neutron Gamma

Ga Ga Ga

Medical Electron Linear Accelerator

Bremsstrahlung photons for photonuclear reactions are obtained using a

Electa TM Synergy TM accelerator, SLi-25.

Primary electron beam is generated by an electron gun with 50 keV

electrons.

Then the beam accelerated in a copper cavity by a 3 GHz (2856MHz to be

exact) radio-frequency with peak power of about 5 MW.

The typical average electron current is about 30 μA for an electron energy

of about 10 MeV,

The SLi-25 is a pulsed linear accelerator with 400 pulses per second and a

pulse length of 3 micro seconds.

The steering and focusing of the beam is achieved by standard magnetic

and electrostatic devices.

e-

h·

The bremsstrahlung field; lateral homogeneity

Spatial beam uniformity at y=0 along

the x-axis

Measurement performed with a matrix

of 32x32 ion chambers for 2 s.

Longer measurement times reduce

the variations.

Bremsstrahlung spectrum at sample position

DETECTORS

A p-type, coaxial, electrically cooled, HPGe gamma-ray spectrometer

40% relative efficiency and 768 eV FWHM at 122 keV for 57Co and 1.85 keV

FWHM at 1332 keV for 60Co

Connected to a NIM consisting of ORTEC bias supply, spectroscopy

amplifier, analog to digital converter and a computer.

Placed into a 10 cm thick lead shield with an inner surface covered by a 2

mm thick copper foil to shield from the X-rays originating in lead

Emitting gamma rays in the energy range between 47 and 1836 keV is

rutinely used for energy calibration.

Configured with 16383 channels and the gain is adjusted: energy resolution

is about 0.18 keV giving a range of detected energies up-to about 3000 keV.

DATA ACQUISITION

PHOTONUCLEAR REACTIONS

Ga-69: 60.1%

Ga-71: 39.9%

THE GALLIUM EXPERIMENT: GAMMA SPECTRUM

THE GALLIUM EXPERIMENT: ENERGY LEVELS

THE PRASEODYMIUM EXPERIMENT:

ENERGY LEVELS

THE SCANDINIUM EXPERIMENT:

ENERGY LEVELS

HALF-LIFE FITS

Secular equilibrium is assumed i.e. T1/2 parent >> T1/2 daughter

min, h, d >> ns, ps

Isotope NUDAT T1/2

σNUDAT

T1/2

σ

68Ga 67.71 m 0.09 67.5 m 0.9 72Ga 14.10 h 0.02 13.9 h 0.2 140Pr 3.39 m 0.01 3.38 m 0.06

142Pr 19.12 h 0.04 20.3 h 0.7 44Sc*(1157) 58.61 h 0.10 59 h 6 44Sc(1157) 3.97 h 0.04 4.04 h 0.02

44Sc*(271) 58.61 h 0.10 60.3 h 1.5

HALF-LIFE RESULTS

for multi-isotop elemements (Ga) we get some systematic

error ~10% for single isotop elements (Pr, Sc) we are in agreament with

the literature and can have similar uncertanties

THE DECAY OF SCANDİNİUM:

(No-secular equilibrium!)

Photo-fission of Uranium-238 Materials

Photo-fission of Uranium-238

Stage 1- To perform photo-fission of the target nuclei Uranium-238, inside compound UO2(NO3)2, was prepared with appropriate geometry for irradiation and detection of the yield with the HPGe detector.

Stage 2- The target was irradiated for 1 hour with 18 MeV bremsstrahlung photons obtained from e-linac.

Stage 3- Fission yield data resulted from photo-nuclear reaction were counted for two days with HPGe.

Stage 4- The spectrum was analyzed to identify the photo-fission yields. The energy and the area of the each peak and half lives of the nuclei of the peaks were determined.

Results

Photo-Fission Yields Energy

(keV)

134Te 210.573

94Y 917.7587

136Pr 999.8549

142Ba 255.0362

142Ba 364.21

142Ba 1093.1321

142Ba 1202.1

138Xe 258.2187

138Xe 396.2359

104Tc 357.632

104Tc 529.4958

104Tc 792.627

Yield identification continues…

SUMMARY & OUTLOOK A unique research center having an accelerator that is capable of

performing spectroscopy and instrumentation

Important to promote Nuclear Science at devoloping countries

Tranining and education facility for the PhD and MSc students: i.e. For the case of Turkey, CERN membership, Nuclear & HEP

studies

Material hardening, space radiation and detector studies: compton background test for AGATA and ELI-NP

Nuclear Reactions: (,n) (,p) (, ) and (, ’) for PR and GDR

Energy Levels and Half-life measurements for proton rich nuclei: Better results

Nuclear structure: level densities and transitions

Nuclear structure: Shape-Phase transitions

Nuclear Astrophysics: Nucleosynthesis for early universe

Applications of Nuclear Techniques from Archeology, Engineering to Agriculture for devoloping countries

Outcomes: First photonuclear paper with local resources

• 2221 Visiting Scientists/researchers on Long term Long-term fellowships fund is available for the following activities in Turkey: Conducting research and development (R&D) • Scientists/researchers on SABBATICAL LEAVE (3 to 12 months): Scholars or academic staff on SABBATICAL LEAVE planning to come to any Turkish university/institution is also funded • Requirements for Beneficiaries: Fellows can be citizen of any country. Fellows should have a PhD degree (or equivalent) • Fellowship Details: A monthly stipend of up to 3.000 US$ for Visiting Scientists. A monthly stipend of up to 3.500 US$ for Visiting Scientists on Sabbatical Leave Travel costs (round trip) and health insurance premiums.

TUBITAK VISITING SCIENTIST PROGRAMME http://www.tubitak.gov.tr/

This research has been supported by TÜBİTAK with grant number 114F220