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Calculation of atomic radiations in nuclear decay – BrIccEmis and beyond

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### Calculation of atomic radiations in nuclear decay – BrIccEmis and beyond

T. Kibèdi, B.Q. Lee, A.E. Stuchbery, K.A. Robinson

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- Talk is largely based on
- Kȧlmȧn Robertson (ANU) Honours project (2010)
- Boon Quan Lee (ANU) Honours project (2012)
- 2012Le09 Lee et al.,
- “Atomic Radiations in the Decay of Medical Radioisotopes: A Physics Perspective”
- Computational and Mathematical Methods in Medicine
- Volume 2012, Article ID 651475, doi:10.1155/2012/651475
- 2011 NSDD meeting (IAEA)
- Radiative and Non-radiative atomic transitions in nuclear decay
- Nuclear and atomic data
- Existing programs to evaluate atomic radiations
- New model based on Monte Carlo approach
- Future directions

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Atomic radiations - Basic concept

- Vacancies on the inner-shell can be produced by
- electron impact
- photo ionization
- ion-atom collision
- internal conversion
- electron capture
- secondary processes accompanying
- b-decay or electron capture

3D

3P

M3

M1

M2

M5

M4

3S

2P

L1

L2

L3

2S

Initial vacancy

1S

K

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Atomic radiations - Basic concept

X-ray emission

3D

3P

M4

M5

M1

M2

M3

3S

2P

L1

L2

L3

2S

X-ray photon

Initial vacancy

1S

K

Ka2 X-ray

1 secondary vacancy

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Atomic radiations - Basic concept

X-ray emission

3D

3P

M5

M5

M1

M1

M2

M3

M4

M4

M3

M2

3S

2P

L2

L3

L2

L1

L1

L3

2S

X-ray photon

Initial vacancy

Initial vacancy

1S

K

K

Ka2 X-ray

1 secondary vacancy

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Atomic radiations - Basic concept

X-ray emission

Auger-electron

3D

3P

M1

M5

M4

M3

M2

M2

M3

M4

M5

M1

3S

Auger-electron

2P

L1

L2

L3

L3

L2

L1

2S

X-ray photon

Initial vacancy

Initial vacancy

1S

K

K

K L2 L3 Auger-electron

2 new secondary vacancies

Ka2 X-ray

1 secondary vacancy

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Atomic radiations - Basic concept

X-ray emission

Coster-Kronig electron

3D

3P

CK- electron

M5

M4

M3

M2

M3

M2

M1

M4

M5

M1

3S

2P

L1

L2

L3

L3

L2

L1

2S

Initial vacancy

X-ray photon

Initial vacancy

1S

K

K

L1 L2 M1 Coster-Kronig transition

2 new secondary vacancies

Ka2 X-ray

1 secondary vacancy

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Atomic relaxation and vacancy transfer

A vacancy cascade in Xe

From M.O. Krause, J. Phys. Colloques, 32 (1971) C4-67

O1,2,3

- Full relaxation of an initial inner shell
- vacancy creates vacancy cascade involving X-ray (Radiative) and Auger as well as Coster-Kronig (Non-Radiative) transitions
- Many possible cascades for a single
- initial vacancy
- Typical relaxation time ~10-15 seconds
- Many vacancy cascades following a
- single ionisation event!

A

A

A

A

A

A

A

A

N4,5

N2,3

KC

N1

A

A

A

M4,5

M3

M2

M1

A

A

L3

L2

L1

X

Initial vacancy

K

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- For a single initial vacancy on the K-shell following nuclear decay

Internal conversion

Number of primary vacancies

Electron capture

X-ray emission

Auger-electron

in an ion

Energy

Intensity

for L1 shell

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Medical applications - Auger electrons

- Biological effect:
- Linear energy transfer LET, keV/mm

electrons

Kassis, Int. J. of Radiation Biology, 80 (2004) 789

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Medical applications - Auger electrons

- 2011 August, INDC International Nuclear Data Committee
- Technical Meeting on Intermediate-term Nuclear Data Needs for Medical Applications: Cross Sections and Decay Data
- Edited by A.L. Nichols, et al.,
- NDC(NDS)-0596

Targeted tumor therapy

Auger emitters: 67Ga , 71Ge, 77Br,99mTc, 103Pd, 111In, 123I, 125I, 140Nd, 178Ta, 193Pt, 195mPt, 197Hg

Regaud and Lacassagne (1927)

“The ideal agent for cancer therapy would consist of heavy elements capable of emitting radiations of molecular dimensions, which could be administered to the organism and selectively fixed in the protoplasm of cells one seeks to destroy.”

(Courtesy of Thomas Tunningley, ANU).

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- Physical approach

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- Auger electron yield per nuclear decay

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- Common problems / limitations
- In some cases neutral atom binding energies are used for atoms with vacancies; i.e. for ions
- Single initial vacancy is considered. Secondary vacancies are
- ignored
- Atomic radiations only from primary vacancies on the K and L shell
- Limited information on sub-shell rates
- Auger electrons below ~1 keV are often omitted

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

BrIccEmis – Monte Carlo approach for vacancy creation and propagation

- Initial state: neutral isolated atom
- Nuclear structure data from ENSDF
- Electron capture (EC) rates: Schönfeld (1998Sc28)
- Internal conversion (IC) coefficients: BrIcc (2008Ki07)
- Auger and X-ray transition rates: EADL (1991 Perkins)
- Calculated for single vacancies!
- Auger and X-ray transition energies: RAINE (2002Ba85)
- Calculated for actual electronic configuration!
- Vacancy creation and relaxation from EC and IC are treated independently
- Ab initio treatment of the vacancy propagation:
- Transition energies and rates evaluated on the spot
- Propagation terminated once the vacancy reached the valence shell

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- Reads the ENSDF file, evaluates absolute decay intensities of EC, GAMMA, CE and PAIR transitions
- Simulates a number (100k-10M) radioactive decays followed by atomic relaxation
- Electron configurations and binding energies stored in memory (and saved on disk). New configurations only calculated if needed. (55Fe: 15 k, 201Tl: 1300k)
- Emitted atomic radiations together with shells involved stored like histories in large files (several Gb)
- Separate files for X-rays and Auger electrons
- Smaller programs to sort/project energy spectra, produce detailed reports

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

111In EC – vacancy propagation

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

2.1726 keV below L-shell BE

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

99mTc atomic radiations – X-rays

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

99mTc atomic radiations – Auger electrons

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

99mTc atomic radiations – Auger electrons

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

BrIccEmis: spectrum from 10 M simulated decay events

No experimental spectrum to compare with

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

111In – experiment vs calculation

E.A. Yakushev, et al., Applied Radiation and Isotopes 62 (2005) 451

- ESCA; FWHM = 4 eV
- Calculations normalized to the strongest experimental line

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

111In – experiment vs calculation

A. Kovalik, et al., J. of Electron Spect. and Rel. Phen. 105 (1999) 219

- ESCA; FWHM = 7 eV
- Calculated energies are higher
- KL2L3(1D2) energy (eV):
- Multiplet splitting could not be reproduced in JJ coupling scheme
- Similar discrepancies have been seen in other elements (Z=47, Kawakami, Phys. LettA121 (1987) 414)

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

K-shell binding energies for superheavy elements (2012Ki04)

2002Ga47 & 2008Th05: Breitmagnetic electron interaction and the quantum electrodynamical (QED) corrections.

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

Breit and other QED contributions (2002Ga47)

Alternative solution:

Semi empirical corrections, like Larkins (1977La19) or Carlson (1977Ca31) used

Z=49 (In)

~60 eV

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

131mXe IT – charge state at the end of atomic relaxation

- Only a handful of measurements exist for ionization by nuclear decay
- 131mXe: F. Pleasonton, A.H. Snell, Proc. Royal Soc. (London) 241 (1957) 141
- 37Ar: A.H. Snell, F. Pleasonton,
- Phys. Rev. 100 (1955) 1396
- Good tool to asses the completeness of the vacancy propagation
- BrIccEmis: mean value is lower by ~0.7-1.0 charge

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

- BrIccEmis: calculation intensive approach (hours to days)
- RelaxData (under development):
- Nuclear decay event (EC or CE) produces a SINGLE INITIAL vacancy
- Considering a single atomic vacancy the relaxation process independent what produced the vacancy
- Compile a database of atomic radiation spectra for
- produced by a single initial vacancy on an atomic shell
- Carry out calculations of all elements and shells
- Example: 55Fe EC, 7 shells for Z=25 and 26, calculated in couple of hours (1 M each shell)
- Replace EADL fixed rates and binding energies from RAINE with GRASP2k/RATIP calculations
- BrIccRelax (under development): Evaluate primary vacancy distribution and construct atomic spectra from the data base (20 seconds for 55Fe EC)

Tibor Kibèdi, Dep. of Nuclear Physics, Australian National University

DDEP Workshop, Paris, 8-10 October 2012

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