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# Hawoong Hong <h-hong@uiuc,edu>
# requesting 3 days, at minimum=2 days
# beamline 33ID, "Phonon dispersion of MgB2"
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# top:/home/www/beamtime-requests/req00258.txt
# UNICAT Member Beam Time Request  #258
# created Thu Apr 04 12:09:45 CST 2002
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beamline:
	33ID

collaboration:
	Yes

contact:
	h-hong@uiuc,edu

days:
	3

description:
	Since superconductivity was found in MgB2 below 40K, there have been enormous number of studies on the properties of MgB2. A few different versions of phonon dispersion have been already published. However, large size single xtals are not available for neutron scattering. There exist only phonon density of state measurments. So far the consesus is that the Mgb2 superconductivity is from ordinary phonon-electron interaction. Therefore determination of phonon dispersion and study of the phonon anomaly during superconducting transition are exteremely important and would have large impact in this area.
	
	Fortunately, the best xtals are available to our group. However, the size is about 50 micron x 50 micron x 1 micron. MgB2 also has small x-ray scattering cross-section. It requires high brilliance beam from undulator.
	
	We will start with room temperature measurements and then proceed to transition experiments in the second run.
	
	Because one unit cell has 3 atoms, we have to deal with 9 branches of phonon dispersion curves. It will be very challeging but will prove the usefulness of our technique.

equipment+required:
	Bruker Diffractometer
	Roper CCD

experiment:
	Phonon dispersion of MgB2

foreign+nationals:
	

hazards:
	

minimumdays:
	2

name:
	Hawoong Hong

new+request:
	on

nonmembers:
	Sung-ik Lee (He does not come to the experiment)

unacceptable+dates:
	


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