[Nexus] nexus units

[Herbert J. Bernstein]

I believe there are two major ways in which monitors are being used:
as a single number representing a count rate, and as two numbers, one
for a count total and the other for the time interval during which the
count total accumulated.  I would suggest supporting both.

On Wed, May 27, 2015 at 11:01 AM, Paul Kienzle <paul.kienzle at nist.gov> wrote:
> 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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>> http://lists.nexusformat.org/mailman/listinfo/nexus
>
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