Detector

My company has three detectors. Do I need three copies/licenses of Angle?

No, one copy will be enough. Angle has no limitations regarding the number of detectors you can define.

We have detectors from ORTEC/AMETEK/EG&G/Canberra/PGT/other. Can we use Angle with them?

Of course. You can use Angle with any semiconductor (Ge) or scintillation (NaI) detector, regardless of manufacturer. You just need to have a detector datasheet showing the detector dimensions and materials used.

Do we need to send our detector to you/manufacturer to characterize it?

No. The only thing you need for characterization is the detector datasheet showing the detector dimensions and materials used. Just enter these data in Angle and your detector is characterized immediatelly! Of course, in order get the final results, i.e. to calculate detector efficiencies for particular counting arrangements, you need, in addition, to experimentally obtain a reference efficiency curve for your detector (efficiency transfer principle).

I am inputting my detector’s dimensions in Angle but I am puzzled with some of the detector’s data terms in the datasheet supplied by the manufacturer.

Indeed, there is no exact/consistent nomination in the literature and among manufacturers for particular detector construction details – different names are often used for the same thing. For example, “housing” could be also a “mount cap”, “inactive Ge layer” could be named “dead layer” or “outside contact layer” etc. In order to avoid confusion/misunderstanding, Angle always – while entering/editing/reviewing the data – displays schematic drawing representing the data being currently entered. While entering the dimensions, a red dimension line is showed on the illustration indicating the required dimension. Thus, it is important what is actually indicated this way on the detector drawing, and not what it is called.

We usually protect our detector by putting a plastic bag over it during the measurements. Can we define this bag in Angle?

Yes. You can define up to four additional absorbing layers in your geometry. Additional absorbing layer is any material gamma-rays encounter on their way from source to detector. For each layer you can define its top and side (relative to the detector) thickness and material.

I would like to create data for a new detector based on an existing one. Do I have to re-type all data again?

No. Just choose the detector you would like to use, click “Edit”, change whatever you want, click the “Save as” button and give a name to the new detector.

This can also be applied to simply vary the parameters of the same detector towards its better characterization (“optimization”) – for example, to estimate the real values of some parameters which are not directly accessible/measurable (dead layers, vacuum dimensions) by comparing Angle calculations with experimental data (measurements).

We have planar detector with core, but it is not possible do define core with planar detector in Angle. What should we do?

Technically, all cylindrical detectors have similar configurations. You can, without any worry, use the option for the equivalent coaxial detector (e.g. “closed-end coaxial”), just be sure to enter the correct dimensions.

Does Angle perform calculations for GMX type detector?

All GMX type detectors belong to “Closed-end coaxial HPGe” in Angle detector specification – they essentially have the same configuration. If the detector is made of (high purity) Germanium, then just choose the one which configuration corresponds to those of your detectors (consult the drawing Angle provides).

Can we change some parameters of demo detectors?

No. Demo detectors are there for demonstration purposes and you cannot change their parameters.

It looks like my detector’s calibration isn’t good anymore because the dead layer drifted into the crystal. Is that a problem given that I am using Angle now?

In principle, when detector characteristics change (worsen) due to ageing (dead layer drifting), then efficiency curve changes/shifts as well, normally to lower values, and especially at lower energies). You should just re-calibrate your detector, obtaining a new reference efficiency curve (REC) and go on. That’s all!

I have noticed my HPGe detector crystal axis is shifted/tilted within the end-cap. Does it affect the accuracy of efficiency calculations? What can I do about that?

Angle does not support that. However this effect usually does not having any dramatic effect. Recommended reading: Literature [15].