Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Speckle correlation as a monitor of X-ray free electron laser induced
  crystal lattice deformation   X-ray free electron lasers (X-FELs) present new opportunities to study
ultrafast lattice dynamics in complex materials. While the unprecedented source
brilliance enables high fidelity measurement of structural dynamics, it also
raises experimental challenges related to the understanding and control of
beam-induced irreversible structural changes in samples that can ultimately
impact the interpretation of experimental results. This is also important for
designing reliable high performance X-ray optical components. In this work, we
investigate X-FEL beam-induced lattice alterations by measuring the
shot-to-shot evolution of near-Bragg coherent scattering from a single
crystalline germanium sample. We show that X-ray photon correlation analysis of
sequential speckle patterns measurements can be used to monitor the nature and
extent of lattice rearrangements. Abrupt, irreversible changes are observed
following intermittent high-fluence monochromatic X-ray pulses, thus revealing
the existence of a threshold response to X-FEL pulse intensity.

19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph