abc%brl-bmd@sri-unix.UUCP (01/22/84)
From: BRINT <abc@brl-bmd> An article in SCIENTIFIC AMERICAN for October, 1983, has re-awakened my interest in cosmology and the like and raised a question to which I probably should know the answer: How is it that the mass of a neutrino is expressed in electron volts? All light appreciated. Brint
gwyn%brl-vld@sri-unix.UUCP (01/22/84)
From: Doug Gwyn (VLD/VMB) <gwyn@brl-vld> Apart from the probability that the proper mass of a neutrino is 0, mass of particles can be expressed in eV by the following reasoning: eV is a unit of energy (that needed to move a unit charge against a 1 Volt potential) m = E / c^2 The MeV or GeV is a convenient measure of particle mass since it relates directly to the characteristics of particle accelerators.
darrelj@sdcrdcf.UUCP (01/22/84)
1 electron volt ~ 1.8E-33 grams.
An EV is a measure of energy imparted to an electron accelerated by a
electric field of 1 volt. Since mass is energy, the conversion is legal.
The reason for use of EV is the mass of a proton is 1.7E-24 grams or just
under 1 giga-electron volt (1GEV) and an electron is around 500,000 EV
(much tidier to read/write than .0000000000000000000000017 g and
.000000000000000000000000001 g respectively and you don't have to worry
about your typesetter miscounting zeros or having trouble with
-27
10 getting formatted right).
--
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,sdccsu3,trw-unix}!sdcrdcf!darrelj
VANBUER@USC-ECL.ARPAJGA%MIT-MC@sri-unix.UUCP (01/22/84)
From: John G. Aspinall <JGA @ MIT-MC>
Date: Sat, 21 Jan 84 20:04:00 EST
From: BRINT <abc at Brl-Bmd>
An article in SCIENTIFIC AMERICAN for October, 1983, has
re-awakened my interest in cosmology and the like and
raised a question to which I probably should know the
answer:
How is it that the mass of a neutrino is expressed
in electron volts?
E = m c^2jonab@sdcrdcf.UUCP (01/23/84)
In article <15829@sri-arpa.UUCP> gwyn%brl-vld@sri-unix.UUCP writes: > >Apart from the probability that the proper mass of a neutrino is 0, > This is not necessarily true. The best that particle physicists can tell is that the mass of the neutrino is very small, on the order of < 10 eV. This can happen because of the Heisenburg Uncertainty Principle, which can be interpreted to say that conservation of mass-energy can be violated as long as the violation occurs for a short enough period of time. I also recall that several of the Grand Unified Field theories actually predict that neutrinos have a small but real rest mass. Considering that the smallest massed particle that we know to exist so far is the electron, and its mass is ~ .5 MeV, the < 10 eV mass of the neutrino may well be beyond our means of measuring yet. -- Jon Biggar {allegra,burdvax,cbosgd,hplabs,ihnp4,sdccsu3,trw-unix}!sdcrdcf!jonab
stern@bnl.UUCP (Eric Stern) (01/23/84)
> An article in SCIENTIFIC AMERICAN for October, 1983, has > re-awakened my interest in cosmology and the like and > raised a question to which I probably should know the > answer: > > How is it that the mass of a neutrino is expressed > in electron volts? > > All light appreciated. > > Brint Simple. The electon volt is a unit of energy, being the amount of energy gained by a particle with the charge equal to that of an electron dropping through a potential difference of 1 volt. The mass of neutrino multiplied by c**2 is an energy( E=mc**2 ) and can be expressed in electon volts. In high energy physics it is common and convenient to use a system of units where c = 1. Then mass and energy are equivalent and equal. Eric G. Stern Suny StonyBrook
stekas@hou2g.UUCP (01/25/84)
"The best that particle physicists can
tell is that the mass of the neutrino is very small, on the order
of < 10 eV."
In fact, I think the latest Russian experiments have actually put a LOWER
bound on the neutrino mass, > 10ev.
Jim