>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 *******************************************
