Article View: sci.physics.cond-matter
Article #52Re: Neutrino Masses
From: Matt Carey
Date: Wed, 18 Jul 2001 18:47
Date: Wed, 18 Jul 2001 18:47
40 lines
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3318 bytes
> No, AFAIK, the number of collisions require to effectively thermalize > a particle is independent of its mass; IIRC, five to ten collisions > is good enough FAPP, as I believe someone posted earlier in this thread. > (Do you know of a contrary reference where it _does_ depend on the relative > masses?) imagine the limit where the neutrino scatters off an essentially infinite mass (runs into a brick wall). The neutrino wouldn't lose any kinetic energy when in bounced off--it would never be thermalized. On the other hand, consider a neutino hitting a mythical rest-neutrino head-on. The neutrino would come to a stop, and the rest-neutrino would speed along at the same speed as the original neutrino. This time, the neutrino is "thermalized" in one collision. The efficiency of losing energy for classical "billiard balls" would depend on the relative masses. Probably the best reference for this would be a series of papers by J.A. Thornton in the 1970s and early 80's on thermalization in sputter processes. This is an effect known in thin film deposition (sputtering). A recent paper would be: Experimental and modeling study of the sputtered particle transport in an r.f. magnetron discharge Clenet F, Briaud P, Lemperiere G, Turban G THIN SOLID FILMS 346 (1-2): 290-298 JUN 1 1999 where, in the abstract, they state: "Owing to their weaker mass value, Ti atoms are faster thermalized than W atoms." In general: If you want to change the direction a particle is moving, run it into something heavy. If you want it to lose energy, run it into something of nearly equal mass. Matt
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 1141dc,f4dfcde22ee4c9c6 X-Google-Attributes: gid1141dc,public X-Google-Thread: 100065,f4dfcde22ee4c9c6 X-Google-Attributes: gid100065,public X-Google-Thread: 104752,f4dfcde22ee4c9c6 X-Google-Attributes: gid104752,public X-Google-Thread: 106ae0,f4dfcde22ee4c9c6 X-Google-Attributes: gid106ae0,public X-Google-ArrivalTime: 2001-07-18 11:44:41 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.mathworks.com!portc03.blue.aol.com!newsjunkie.ans.net!news.chips.ibm.com!newsfeed.btv.ibm.com!news.btv.ibm.com!not-for-mail From: Matt Carey <matt.carey@ieee.org> Newsgroups: sci.physics.cond-matter,sci.materials,sci.mech.fluids,fj.sci.matter Subject: Re: Neutrino Masses Date: Wed, 18 Jul 2001 11:47:29 -0700 Organization: IBM Global Services North -- Burlington, Vermont, USA Lines: 40 Message-ID: <3B55D9C1.4F82F695@ieee.org> References: <a786eec.0107151054.5e5c867b@posting.google.com> <3B51F2D9.CEB79A8B@hate.spam.net> <3B5390E4.6056173A@ieee.org> <3B54A1A6.BE529082@grc.nasa.gov> <3B54DB55.4F633BDA@ieee.org> <m2y9pnm34i.fsf@pusch.xnet.com> <3B55C1DC.E342796E@ieee.org> <m2elrem90k.fsf@pusch.xnet.com> Reply-To: matt.carey@ieee.org NNTP-Posting-Host: carey1.almaden.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: news.btv.ibm.com 995481877 18486 9.1.18.139 (18 Jul 2001 18:44:37 GMT) X-Complaints-To: news@btv.ibm.com NNTP-Posting-Date: 18 Jul 2001 18:44:37 GMT X-Mailer: Mozilla 4.72 [en] (Windows NT 5.0; U) X-Accept-Language: en