title: A dynamic synchrotron X-ray imaging study of effective temperature in a vibrated granular medium.
abstract: We present a dynamic synchrotron X-ray imaging study of the effective temperature Teff in a vibrated granular medium. By tracking the directed motion and the fluctuation dynamics of the tracers inside, we obtained Teff of the system using the Einstein relationship. We found that as the system unjams with increasing vibration intensities Γ, the structural relaxation time τ increases substantially which can be fitted by an Arrhenius law using Teff. And the characteristic energy scale of structural relaxation yielded by the Arrhenius fitting is E = 0.20 ± 0.02pd(3), where p is the pressure and d is the background particle diameter, which is consistent with those from hard sphere simulations in which the structural relaxation happens via the opening up of free volume against pressure.
authors.affiliation: Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240, China. yujiewang@sjtu.edu.cn.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Cao
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Zhang
authors.forename: Binquan
authors.initials: B
authors.lastname: Kou
authors.forename: Xiangting
authors.initials: X
authors.lastname: Li
authors.forename: Xianghui
authors.initials: X
authors.lastname: Xiao
authors.forename: Kamel
authors.initials: K
authors.lastname: Fezzaa
authors.forename: Yujie
authors.initials: Y
authors.lastname: Wang