[Nexus] nexus units

[Paul Kienzle]

Tim,

To be clear, I simply scanned all fields and collected the units 
without checking that the units were appropriate for the field.
The resulting list seemed interesting, hence my email.

The only count rate that I found was for ANSTO monitors, which
uses count/sec for the bm1_event_rate and the bm2_event_rate
fields.  Since count and sec are in the udunits database, this 
is entirely appropriate.  

Hz is used for source frequency at IPNS and sampling frequency 
at Soleil, so again the usage is appropriate.  

I was considering Hz or Bq for count rate, but the SI brochure 
says the following:

    The hertz is used only for periodic phenomena, and the 
    becquerel is used only for stochastic processes in 
    activity referred to a radionuclide.

so count/sec it is.

- Paul


On May 26, 2015, at 5:20 PM, Tim Gruene <tgruene at gwdg.de> wrote:

> Dear Paul,
> 
> I am not sure you appreciate comments or if your email is meant purely
> informatively.
> 
> Some of the units listed below are clearly not 'rates' - or could you
> explain how 'detectors' or 'Angstroem' etc. are units for rates?
> 
> Wouldn't it be better to reject files containing such units and asking
> the maintainer to use the format properly?
> 
> I've seen nexus files which were completely useless because the fields
> were improperly used. Don't people think that accepting those units
> which are none will contribute to spoiling the idea behind hdf/nexus?
> 
> Best regards,
> Tim
> 
> On 05/26/2015 03:28 PM, Paul Kienzle wrote:
>> Hi,
>> 
>> When trying to decide what units to use for monitor rate, I wanted to know what 
>> was already in use in the NeXus world.
>> 
>> I wrote a little script (see attached) to walk the github 
>> nexusformat/exampledata repo and list all the units used in the files.
>> 
>> The results are shown below.
>> 
>> Many thanks to those facililities that have supplied data files (Soleil, APS, 
>> IPNS, ANSTO and SINQ).  I’ll include some NCNR files once we have settled on the 
>> format.
>> 
>> I updated units.py to accept all these units.  This should be able to replace 
>> the version in bindings/python/nxs.
>> 
>>  - Paul
>> 
>> Paul Kienzle
>> paul.kienzle at nist.gov
>> 
>> 
>> Note: facility “code” refers to SINQ.
>> ============================================================
>> unit               facility
>> ============================================================
>>                    : Soleil
>> A                   : APS, Soleil
>> Angstroem           : code
>> Hz                  : IPNS, Soleil
>> K                   : ANSTO, code
>> MW                  : ANSTO
>> RPM                 : code
>> User Unit           : Soleil
>> V                   : Soleil
>> bars                : IPNS
>> count               : ANSTO
>> count/sec           : ANSTO
>> counts              : code, IPNS
>> countsOrseconds     : code
>> degree              : code
>> degrees             : ANSTO, APS, IPNS
>> detectors           : code
>> h                   : Soleil
>> keV                 : APS, Soleil
>> ls-1                : ANSTO
>> m                   : APS, code, IPNS
>> mA                  : Soleil
>> mRad                : Soleil
>> meV                 : code, IPNS
>> microseconds        : ANSTO, IPNS
>> mm                  : ANSTO, code, Soleil
>> ms                  : Soleil
>> nm                  : code
>> rpm                 : ANSTO, code
>> secORcounts         : code
>> seconds             : ANSTO, code
>> us                  : code
>> °C                  : Soleil
>> Å                   : Soleil
>> ============================================================
>> _______________________________________________
>> NeXus mailing list
>> NeXus at nexusformat.org
>> http://lists.nexusformat.org/mailman/listinfo/nexus
>> 
> 
> -- 
> --
> Dr Tim Gruene
> Institut fuer anorganische Chemie
> Tammannstr. 4
> D-37077 Goettingen
> phone: +49 (0)551 39 22149
> 
> GPG Key ID = A46BEE1A
> 
> 
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