Labor für Radioisotope

Measurement devices and methods at LARI

Liquid scintillation counting

Liquid sctinllation counting (LSC) is ideal for measuring the activity from betaminus radiation even for radionuclides with low decay energy.
On our counters we regularly measure samples for H-3, C-14, P-32, P-33, Ni-63 as well as other radionuclides.
Important: Whilest being perfect for measuring the activity in a given samples, it can be difficult or even impossible to identify unknown radionuclides by LSC. Therefore, LSC is mainly used for samples where
(a) The dominant radionuclide is known, e.g. when you labelled the sample with a radioactive tracer, or
(b) You are generally interested to measure the total activity of a sample to decide whether it shows elevated activity (e.g. in contaminations samples)

Gammaspectrometry

We have three high-purity germanium detectors (HPGe) for measuring gamma radiation in samples.
In contrast to beta-emitters, gamma-emitting radionuclides show a characteristic line spectrum, which allows simultaneous measurement of the activity of a sample and the identity of the radionuclides present. This comes at a cost, though: High-quality gammaspectrometry can take several days of measurement for a single sample.
For fast and fully automated measurements of samples labelled with gamma-emitting radionuclides, we alternatively can make use of our Gammacounter. Whilest lacking precision, it allows extremely fast measurements of many samples in short time.
Please note: In April 2024, two of our outdated HPGes will be replaced by new devices. We expect some delays with regard to measurements and sample preparation during this time, but the expected improvements of results should be more than worht it.

I am interested in submitting samples for gammaspectrometry

Phosphoimaging

In two-dinemsional objects, Phospoimaging can help localising activity from radionuclides and visualize activity distribution semi-quantitatively.
It can be used for leaves, roots, or even whole plants.
However, objects should be dried to avoid problems from shielding of radiation by water.

Elemental Analyzer (C:N)

In addition to measurement of radioactive samples, we also offer basic elemental analysis for quantification of carbon (C) and nitrogen(N) content.
Samples have to be submitted milled and dried.
If you do not have the facilities for milling samples yourself, there is limited capacity for sample milling at the department of Forest Botany. This only includes access to and intructions regarding the mills, the milling has to be done by users themselves.


I am interested in submitting samples for C:N analysis