Archive for the ‘FAQs’ Category

Ra-226 irradiations now possilbe with webKORIGEN

March 22nd, 2019

Qu. (from D. B. Garching, Germany):
Dear Nucleonica Team, if I let Ra-226 irradiate in a certain flux for a certain time, why I do not get nuclides with mass numbers higher than 226?

Ans. (Nucleonica Team)
This problem has now been resolved.

Results are shown below for an irradiation of Ra-226 (2g) in a dedicated facility with a thermal neutron flux of 2e14 neutrons per cm2 per s for a period of 100 days.
Ra226 Irrad

More info…
– webKORIGEN++ neutron activation wiki page

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Problem with using mixtures in DELNuS++

February 25th, 2019

Some of our users have reported that the results of a decay calculation using DELNuS++ for a mixture does not give the same result as the sum of the results for the single nuclide calculations.
As an example, the activity of Cs137 or Kr85 produced from a mixture of Cf252 and Cf250 is almost a factor two higher that from the sum of the results using the single nuclides Cf252 and then Cf250.
The problem has now been identified and resolved.
The results obtained using DELNuS++ for the mixture are now consistent with the sum of the results for the individual component nuclides. The results also agree with those obtained using the Decay Engine++ (which can also account for fission products).

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Ambient dose rates caused by different types of radiation

February 8th, 2019

Ambient dose equivalent H*(d) is the normal monitoring (area monitoring) quantity for X, gamma and neutron radiation where d is the depth at which the dose applies. International convention in radiation protection is to use the ambient dose equivalent at 10 mm depth i.e. H*(10). The ambient dose gives a conservative estimate of the effective dose a person would receive when staying at the point of the monitoring instrument (NPL).
In Nucleonica applications, the photon (X+gamma), beta, and neutron doses are calculated separately using analytical and semi-analytical formulae. To obtain the (total) ambient dose H*(d), these individual doses must be added. Following Otto, the ambient dose from a radionuclide can be represented as a sum of components caused by different radiation types, i.e.
ADR_Radiations3This is the notation which will be used in various Nucleonica applications for ambient doses and dose rates i.e.
ADR_Radiations4
For control of doses to skin and lens of eye, the directional dose equivalent is used. The directional dose equivalent denoted by H′(d) is intended for use with less penetrating radiation such a beta particles. Its main use is for skin dose at a depth of 0.07 mm. For beta radiation and electrons, for example, this is denoted as i.e. H'(0.07)e.
ADR_Radiations6

More info…
– T. Otto, Personal Dose-Equivalent Conversion Coefficients for 1252 Radionuclides, Radiation Protection Dosimetry (2016), Vol. 168, No .1, pp1-70. Link
NPL: Measurement of dose rate
Operational quantities (Wikipedia)

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Energy deposited in matter by nuclear and electronic stopping processes

January 14th, 2019

Qu. (from G.D. Fz-Juelich):
Dear Nucleonica Team, we have the following question regarding the energy deposited in matter by nuclear and electronic stopping processes:
We are interested in the respective contributions of nuclear stopping and electronic stopping to the (integral) energy deposited in solid materials during irradiation with heavy ions with defined energy (e.g. Au-197 ions with 5 MeV). Using the Range & Stopping Power++ App in Nucleonica, the results table provides only the values for the electronic and nuclear stopping at the materials’ surface (e.g. in keV/µm at depth 0 µm).
Bragg curve for 5MeV Au-197 on Water (liquid)
Integrating the Bragg curves (using the downloaded graph data) by the trapezoidal method suggests that the sum of the energies deposited by nuclear and electronic amounts only to 80 to 90% of the initial energy of the projectile. Is this correct (and if so, where is the remaining energy), and is there a more convenient way to directly calculate the amounts of energy deposited by each nuclear and electronic stopping, respectively, using either the Range & Stopping Power++ App in Nucleonica or SRIM/TRIM.

Ans. (Nucleonica Team)
The difference in the sum of the energies deposited by nuclear and electronic contributions come most probably from the limitations of numerical calculation procedure.
The difference is not due, for example, to Bremsstrahlung since Bremsstrahlung is considered only for light particles, i.e. incoming electrons and positrons. The R&SP++ app does not calculate Bremsstrahlung for heavy ions. This difference probably comes from the numerical procedure. Note the R&SP++ app uses the SRIM engine for heavy ions, so R&SP++ app and SRIM’s results are the same.
The Nucleonica Team will investigate this difference further.

More info…
Range and Stopping Power wiki page

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Use of Concise Notation for Half-life Uncertainties

November 28th, 2018

The use of the concise notation is best demonstrated with an example. Research papers often publish half-lives in so-called ‘non-concise’ form. As an example, the half-life of the alpha emitter Gd-148 has been measured to be T1/2= 70.9 ± 1.0y. When this information is published in, for example, ENSDF, NDS etc. a more concise notation is used as shown in the diagram below for Gd-148 i.e. T1/2(y) = 70.9 10 where it understood that the number in italics is the numerical value of the standard uncertainty referred to the corresponding last digits of the quoted result.
Gd148 Extract from ENSDF for nuclear data on Gd-148.

As another example, the half-life of Po-209 is given in the original scientific paper as as T1/2(y) = (125.2 ± 3.3) a. In Nucleonica’s Nuclide Datasheets, however, the half-life is given as T1/2(y) = 125.2 (33) a. Notice the notation follows that of NIST which is slightly different from the ENSDF above (NIST has the uncertainty in brackets, non-italic e.g. (33); ENSDF has the uncertainty in italic withour brackets e.g. 33). Further examples of uncertainties notations are shown below.
NDS-Uncertainties For further information see the references below.

References
Use of concise notation for data uncertainties
Standard Uncertainty and Relative Standard Uncertainty
ENSDF manuel; Note on uncertainties is on page 104
NDS Notes on page 7

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How to add Nucleonica login to your smartphone/tablet homescreen

November 23rd, 2018

Launch the mobile browser and open the website or web page you want to pin to your home screen. Use https://nucleonica.com/?login to pin the login page for fast access (If you do not see the login page, clear the cache using Ctrl+F5). Tap the menu button and tap Add to homescreen. You’ll be able to enter a name for the shortcut and then Chrome will add it to your home screen.
More information

Mobile-Nuc2On the homescreen shown above, four Nucleonica pages have been added:
1. Nucleonica Login (click on this icon to get to the login page. Click again to enter the portal, assuming username and password have been saved).
2. NucleonicaBlog (click here to go directly to the latest information on the blog)
3. Nucleonica Faqs (Click here to go directly to the Frequently Asked Questions)
4. Nucleonica Wiki (Click here to go directly to the Nucleonica wiki)

See also Nucleonica for Smartphones

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Unidentified peaks in I-125 spectrum

May 30th, 2018

Qu. (from Z. S. JRC Karlsruhe) Using the Gamma Spectrum Generator app in Nucleonica I have created a gamma spectrum for I-125 (shown below). Comparing the results from the Nuclide Datasheets++, I find the three lines at approx. 35, 31, 27 keV (see inset from the Datasheets++). Where do the extra peaks at approx. 21 and 17 keV come from?
UnPeaksAns. (Nucleonica Team)
The additional lines from the I-125 spectrum are X-escape peaks.

Ge emits X-rays at approx. 10 keV (Intensity 48%), 11 keV (intensity 6%), and about 1.2 keV (Intensity 0.5%) so Xesc-peaks can be expected at:
21 keV = 31 keV – 10 keV
20 keV = 31 keV – 11 keV and 21 -1.2

17.6 keV = 27.5 – 10 keV
16.5 keV = 27.5 – 11 keV and 17.6 – 1.2

25.4 keV = 27.5 -1.2 keV
The relative intensities correspond about to the relative Ge X-ray intensities.
More information:
X-Ray Emission Lines
X-ray Escape Peaks

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Feedburner Deactivated

May 3rd, 2018

Because of recent problems, the Feedburner service for managing RSS feeds has been deactivated. The Nucleonica Blog posts are now sent directly to Nucleonica’s Networking page using the WordPress feeds. Users can no longer receive these post feeds via email. However, the most recent feeds are shown directly on the Networking page.

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SSL secure access active again

April 9th, 2018

SSL secure access has been reactivated.
Access to Nucleonica again available now through https://nucleonica.com.

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SSL temporally disabled

March 28th, 2018

SSL temporally disabled

Due to problems with the renewal of the nucleonica.com SSL certificate, the SSL (https) has been temporally disabled.

As soon as the problem has been resolved, the SSL will be reactivated.

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