Yes, I have read that paper (a seminal one and the source of the "Henderson limit," no?), and saw that the best "deal" is electrons, I think, but I was just delighted to learn that it doesn't happen in practice. As I recall, x-rays are the worst deal?
JPK On Thu, Sep 22, 2011 at 11:58 AM, Murray, James W <j.w.mur...@imperial.ac.uk> wrote: > >>Wow, neutrons are pretty cool! No radiation damage--and time >>resolution? > > Actually, as calculated by Richard Henderson in 1995, there is non-negligible > radiation damage from neutrons due to infrequent but energetic nuclear > reactions. The reason that radiation damage by neutrons is not observed in > practice is that neutron sources are so weak. > > The potential and limitations of neutrons, electrons and X-rays for atomic > resolution microscopy of unstained biological molecules. > Henderson R. > Q Rev Biophys. 1995 May;28(2):171-93. > > best wishes > > James > > -- > Dr. James W. Murray > David Phillips Research Fellow > Division of Molecular Biosciences > Imperial College, LONDON > Tel: +44 (0)20 759 48895 > ________________________________________ > From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Jacob Keller > [j-kell...@fsm.northwestern.edu] > Sent: Thursday, September 22, 2011 5:43 PM > To: CCP4BB@JISCMAIL.AC.UK > Subject: Re: [ccp4bb] Neutron data collection > > Wow, neutrons are pretty cool! No radiation damage--and time > resolution? I guess this is since they have much higher energy, and > are measurable individually? What are the numbers for fluxes > (neutrons/sec)? Are the neutrons all at one energy, or is there a > bandwidth? > > JPK > >> With X-rays, Laue diffraction leads to some systematic overlap as >> reflections from different wavelengths fall on the same detector position, >> and this cuts into completeness. >> >> With neutrons, it is possible to use a time-resolved detector such that all >> events are time-stamped, and the reflections from lower energy neutrons do >> not overlap with those of higher energy neutrons (neutrons having measurable >> mass, and thus noticable velocity differences). I know that this is >> possible, I do not know whether it is commonplace. >> >> See, for example: >> Protein crystallography with spallation neutrons: the user facility at Los >> Alamos Neutron Science Center (2004) P. Langan, G. Greene & B.P. Schoenborn, >> J. Appl. Cryst. 37(1) 24-31. >> >> >> -- >> ======================================================================= >> All Things Serve the Beam >> ======================================================================= >> David J. Schuller >> modern man in a post-modern world >> MacCHESS, Cornell University >> schul...@cornell.edu >> > > > > -- > ******************************************* > Jacob Pearson Keller > Northwestern University > Medical Scientist Training Program > cel: 773.608.9185 > email: j-kell...@northwestern.edu > ******************************************* > -- ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program cel: 773.608.9185 email: j-kell...@northwestern.edu *******************************************
