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RE: Conversion of Half-life Years to Seconds
Hi Doug,
thanks! This means that my year -> seconds multiplier should to be
changed from 31,557,600 to 31,556,952. I'll take the Gregorian instead
of the real value since this would produce the closest match to
the caledars in use?
Dimiter
--------------------------------------------------------------------
Dimiter Popoff
Transgalactic Instruments, Gourko Str. 25 b, 1000 Sofia, Bulgaria
http://transgalactic.freeyellow.com
> From: "Taylor, Douglas" <Douglas.Taylor@shawgrp.com>
> To: "Dimiter Popoff" <tgi@cit.bg>, <radsafe@list.vanderbilt.edu>
> Subject: RE: Conversion of Half-life Years to Seconds
> Date: Thu, 11 Dec 2003 08:44:49 -0600
>
>
> Dimiter,
> In 46BC the Roman emperor Julius Caesar set the standard year
> at 365 days with every fourth year having 366 days (Julian calendar).
> Every four year period has exactly 1461 days so the Julian year
> is exactly 365.25 days (31,557,600 seconds). The Julian year
> is slightly long of the actual year by about 11 minutes. By the
> time of the Renaissance this slight difference had added up to
> about 10 days, so that the Spring equinox was occurring on March
> 11th instead of March 21st. In 1582 Pope Gregory XIII dropped
> 10 days from the year, so the day after October 4th was October
> 15th. The Pope adjusted the Julian calendar by decree so that
> years divisible by 100 are not leap years unless they are also
> divisible by 400, (2000 and 2004 are leap years while 2100, 2200
> and 2300 are not). The Gregorian calendar is the accepted civil
> colander around the world. The Gregorian year (365.2425 days)
> is still long of the actual year, or "tropical year", by only
> about 28 seconds. The tropical year is measured as the period
> of time required for the sun to mark successive summer solstice
> in the southern hemisphere by arriving at the Tropic of Capricorn,
> which is accepted as 365.242199 days (31,556,925.9747 seconds).
> I hope that helps.
>
>
> Doug Taylor
> WPP Laboratory Manager
> Shaw Environmental
>
>
>
> -----Original Message-----
> From: Dimiter Popoff [mailto:tgi@cit.bg]
> Sent: Wednesday, December 10, 2003 6:41 PM
> To: radsafe@list.vanderbilt.edu
> Subject: Re: Conversion of Half-life Years to Seconds
>
>
>
> I am not sure if this correction is necessary because of my non-native
> English, but to me
>
> " now that you know you have asked the wrong question, ..."
>
> in the context of the message exchange on this thread means the same like
>
> " now that you've been told you have asked the wrong question, ..." .
>
>
> Again, I am also curious what the answer to the question is - and I
> certainly believe it is a justified question to ask.
> I would guess the answer is 365.25 for practical reasons (see my
> former message, quoted below).
>
> Dimiter
>
>
> > Cc: <radsafe@list.Vanderbilt.Edu>
> > To: Leo M. Lowe <llowe@senes.ca>
> > From: Dimiter Popoff <tgi@cit.bg>
> > Subject: Re: Conversion of Half-life Years to Seconds
> > Date: Thu, 11 Dec 2003 0:05:30 +0200
> >
> > Leo Lowe,
> >
> > now that you know you have asked the wrong question, may I re-ask it:
> >
> > > Which "year" is used by the standards organizations, such as NIST, when
> > > publishing half-lives?
> >
> > Several years back, when I was writing my spectrum evaluation software,
> > I programmed the interactive nuclide library to switch the unit of the
> > half-life every time you click it.
> > I had the same question then - but given the issue was of no analytical
> > concern, I just took 365.25 days/year and called it a day. Also, this was
> > the better choice for me because in the sample report you can click and
> > edit the date of any isotope and see what its activity was/will be then;
> > this implies 365.25 precisely.
> >
> > I certainly would be curious if there is a "standard" for that.
> >
> > Dimiter
> >
> > --------------------------------------------------------------------
> > Dimiter Popoff
> > Transgalactic Instruments, Gourko Str. 25 b, 1000 Sofia, Bulgaria
> > http://transgalactic.freeyellow.com
> >
> >
> >
> >
> > > I want to calculate relatively precisely the specific activities of
> > > radionuclides with half-lives that are given in units of years. This
> > > requires a conversion from "years" to seconds.
> > >
> > > So which "year" should I use: the calendar year (365 days), the mean solar
> > > year (365.24219 days), the sidereal year (365.25636 days), ....? (where 1
> > > day = 24 hours = 86,400 seconds).
> > >
> > > Which "year" is used by the standards organizations, such as NIST, when
> > > publishing half-lives?
> > >
> > > Regards,
> > >
> > > Leo M. Lowe, Ph.D., P.Phys.
> > > Principal, Senior Health and
> > > Environmental Physicist
> > >
> > > SENES Consultants Limited
> > > 121 Granton Drive, Unit 12
> > > Richmond Hill, Ontario
> > > Canada L4B 3N4
> > > Tel: (905) 764-9380
> > > Fax: (905) 764-9386
> > > llowe@senes.ca
> > > www.senes.ca
> > >
> >
>
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