Frequently Asked Questions (FAQs)
  • Traditional Quantities and Units
  • Photon Dose Equivalent Hx
  • »New« Dose Equivalents
  • What means »PTB approved« and »PTB certified«?
  • What is the Significance of Automess Calibration Certificates?
  • Recommendations for Periodical Checks

All these subjects are discussed as General Notes on our Products in the »Products« category.

See Radiation Quantities and Units for more detailed information on radiation quantities.


  • Why are »/E« models of 6150AD and probes not compatible with old Hx models?

This is not a barrier we installed to force our customers to buy new instruments. When first creating H*(10) members of the 6150AD Family of Products, we started calling them »/H« models. When applying for the PTB approval of the /H models, we learned about a German regulation requiring basic meter and probes always to use the same quantity. According to this regulation, a new 6150AD H*(10) model must not work with old Hx probes, and new H*(10) probes must not work with old 6150AD Hx models. For this reason we had to create the »/E« models particularly for the German market. »/E« models are identical to »/H« models except that they use different internal probe codes. For international users not bound to German regulations we strongly recommend »/H« models over »/E« models because this will not result in compatibility problems. This is why we almost ignore »/E« models in the English edition of our homepage.


  • Can old Hx models be upgraded to H*(10) models?

Yes. Many of our (domestic) customers already made use of this opportunity. For technical reasons some upgrades are only possible from certain serial numbers on:

  • Upgrade 6150AD1 to AD1/H: always possible.
  • Upgrade 6150AD1/3/5 to AD5/H: from S/N 64040 up.
  • Upgrade 6150AD2 to AD2/H: always possible.
  • Upgrade 6150AD2/4/6 to AD6/H: from S/N 65602 up.
  • Upgrade Gamma Probe 6150AD-15 to 6150AD-15/H: from S/N 110050 up.
  • Upgrade Gamma Probe 6150AD-18 to 6150AD-18/H: from S/N 112235 up.
  • Upgrade Teletector Probe 6150AD-t to 6150AD-t/H: always possible.
  • Upgrade Scintillator Probe 6150AD-b to 6150AD-b/H: always possible.
  • Upgrade Teletector 6112M to 6112M/H: always possible.
  • Upgrade Scintomat 6134 to 6134/H: always possible.
  • Upgrade Scintomat 6134A to 6134A/H: always possible.

  • I still have dose rate meters for the old quantity Hx (e.g., 6150AD and probes). How do they respond to the new quantity H*(10)? Can I still use these instruments?

Generally, new H*(10) meters indicate more, where the increase ranges from a few percent to approximately 50 percent depending on photon energy. This is not even so much when considering the tolerances permissible for radiation meters. Paradoxically it is even possible, although not very likely, than an H*(10) meter (from manufacturer A) makes full use of negative tolerances and thus indicates less than an Hx meter (from manufacturer B) which makes full use of positive tolerances. However, this technical fact is more a consolation than legally significant. If H*(10) is the legal quantity in your country, you will probably have to use H*(10) instruments for officially required measurements. On the other hand, should you use the instruments for other than officially required purposes, you may still use them. Following a former recommendation of the German radiation protection committee, you may multiply your »old« measurements by a factor of 1.3 thereby »converting« them to the new quantity H*(10). This conversion is a compromise referring to a radiation field with unknown photon energy, where this compromise will underestimate the radiation field and thus the radiation hazard in rare cases, but will overestimate it in the very most cases.


  • I still have personal dosimeter for the old quantity Hx (e.g., ALADOS Digital Dosimeters, Pen Dosimeters SEQ5/6R). How do they respond to the new quantity Hp(10)? Can I still use these instruments? If not, can I have them upgraded?

In case of personal dosimeters the differences are even less pronounced than in case of the dose rate meters (area meters) just discussed. Because they are worn on the body, even old personal dosimeters measure Hp(10) quite well, particularly at higher photon energies, see our leaflet on this subject. However, this is again a technical fact with little or no legal significance. If Hp(10) is the legal quantity in your country, you will probably have to use Hp(10) dosimeters for officially required measurements. On the other hand, should you use the dosimeters as a non-obligatory supplement to legal passive Hp(10) dosimeters (film, TLD), it may be appropriate to continue using your old dosimeters.

Unfortunately, old ALADOS Dosimeters cannot be upgraded to new ALADOX Dosimeters because the interior of both models is too different.

Old Pen Dosimeters cannot be upgraded, and new ones are out of production.


  • The energy range of radiation meters is often specified up to 3 MeV or even less than that. How do instruments respond to higher photon energies?

This question is frequently asked because of the 6 MeV radiation originating from N-16 in nuclear facilities. Energy compensated GM tubes always over-respond at such high energies. We have prepared a leaflet on this subject.


  • I measured dose rate at various distances from the source and noticed deviations from the 1/r² law. What's the reason?

The 1/r² law is only valid if some conditions are met. We have prepared a leaflet on this subject.


  • What do I have to observe when handling Check Sources?

This subject is treated in Check Sources in the »Products« category.


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