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This Week

Aug 28
Thursday

Hard X-ray Nanofocusing at Low-emittance Synchrotron Radiation Sources

Speaker: Prof. Dr. Christian Schroer, DESY/University of Hamburg
APS Upgrade Seminar
401/A1100 @ 1:30 PM
View Description
X-ray scanning microscopy relies on intensive nanobeams generated by imaging a highly brilliant synchrotron radiation source onto the sample with a nanofocusing X-ray optic. Here, using a Gaussian model for the central cone of an undulator source, the nanobeam generated by refractive X-ray lenses is modeled in terms of size, flux and coherence. The beam properties are expressed in terms of the emittances of the storage ring and the lateral sizes of the electron beam. Optimal source parameters are calculated to obtain efficient and diffraction-limited nanofocusing. With decreasing emittance, the usable fraction of the beam for diffraction-limited nanofocusing experiments can be increased by more than two orders of magnitude compared with modern storage ring sources. For a diffraction-limited storage ring, nearly the whole beam can be focused, making these sources highly attractive for X-ray scanning microscopy.

C. G. Schroer, G. Falkenberg, JSR 21, 2014 DOI 10.1107/S1600577514016269
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Aug 28
Thursday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 2:30 PM
Aug 29
Friday

Recent Development in Cryogenic X-ray Microscopy and Applications

Speaker: Si Chen, Advanced Photon Source
XSD Presentation
402/E1100 @ 11:00 AM
View Description
In this presentation, I will speak on the development in cryogenic X-ray fluorescence (XRF) microscopy in the past three years at the APS, including the Bionanoprobe (BNP) at LS-CAT and a cryojet-equipped microprobe at 2IDD beamline and their applications. Hard XRF microscopy is one of the most sensitive techniques for studying trace elements within biological samples and other soft materials. Conventional sample preparation methods usually involve dehydration, which removes water and may consequently cause structural collapse. Radiation-induced artifacts may also become an issue, particularly as the spatial resolution increases beyond the sub-micrometer scale. To allow imaging under hydrated conditions, close to the ‘natural state’, as well as to reduce structural radiation damage, we have developed the BNP. It is a scanning XRF nanoprobe with cryogenic capabilities, dedicated to studying trace elements in frozen-hydrated biological systems and other soft materials. It provides a spatial resolution of 30 nm for both two- and three-dimensional imaging. In addition to life sciences, other fields of research, such as materials science, also benefit from the use of BNP mainly due to its high spatial resolution and low temperature capabilities. To accommodate the increasing requests of performing cryogenic experiments, we have also developed a cryojet-equipped XRF microprobe by implementing a cryojet to the XRF microprobe at 2IDD beamline with optimized configuration. This technical innovation is highly transferable in the way that a cryojet can be integrated on most existing microprobes with minimal instrumentation.
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Aug 29
Friday

Image Reconstruction Advancements for Absorption- and Phase-contrast Tomography

Speaker: Mark Anastasio, Washington University
XSD Presentation
401/A1100 @ 12:00 PM
View Description
In this talk we review recent advancements in image reconstruction methodologies for a variety of X-ray imaging problems. Even with hardware acceleration, the overwhelming majority of available iterative algorithms for 3D image reconstruction that implement non-smooth regularizers remain computationally burdensome and have not been translated for routine use in time-sensitive applications. In this work, two accelerated variants of the fast iterative shrinkage thresholding algorithm (FISTA) for image reconstruction in absorption- and propagation-based X-ray computed tomography (CT) are proposed. The first algorithm seeks to minimizes a penalized least squares (PLS) cost function involving a TV penalty while the second assumes a penalty formed as the sum of a TV penalty and a wavelet-sparsified l1-norm of the object. We also describe an improved image reconstruction approach for grating-based X-ray phase-contrast CT, in which the 2nd order statistical properties of the object property sinograms are exploited, including correlations between them. The problem is formulated within a multi-channel (MC) image reconstruction algorithm framework in which the three object properties are simultaneously estimated. An algorithm based on the proximal point algorithm and the augmented Lagrangian method are proposed to rapidly solve the MC reconstruction problem.
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Upcoming

Sep 3
Wednesday

MAX IV - Pushing the Limits at a Light Source

Speaker: Christoph Quitmann, MAX IV Laboratory
APS Colloquium
402/AUD @ 3:00 PM
Sep 18
Thursday

EPICS Training 2014 - Introduction to EPICS and Channel Access Basics

Speaker: Nicholas Schwarz, Andrew Johnson
APS Course
401/A1100 @ 1:00 PM
View Description
1:00 PM - Introduction to Training - Nicholas Schwarz

1:15 PM - Introduction to EPICS - Andrew Johnson

2:45 PM - Channel Access (CA) Basics - Andrew Johnson
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Sep 19
Friday

EPICS Training 2014 - Channel Access Clients - MEDM

Speaker: Jim Stevens
APS Course
401/A1100 @ 2:00 PM
Sep 24
Wednesday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 2:30 PM
Oct 9
Thursday

EPICS Training 2014 - Channel Access Clients - caQtDM

Speaker: Jim Stevens
APS Course
401/A1100 @ 10:00 AM
View Description
10:00 AM - Channel Access Clients - caQtDM Lecture and Tutorial - Jim Stevens
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Oct 10
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Oct 16
Thursday

EPICS Training 2014 - More Channel Access Concepts

Speaker: Andrew Johnson
APS Course
401/A1100 @ 1:00 PM
Oct 16
Thursday

EPICS Training 2014 - Channel Access Programming in C and Perl

Speaker: Andrew Johnson
APS Course
401/A1100 @ 1:30 PM
Oct 17
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Oct 24
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Oct 24
Friday

EPICS Training 2014 - Channel Access Programming in Python

Speaker: Matt Newville
APS Course
401/A1100 @ 2:00 PM
Oct 29
Wednesday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 2:30 PM
Oct 31
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Nov 6
Thursday

EPICS Training 2014 - IOC Database Principles

Speaker: Andrew Johnson
APS Course
401/A1100 @ 1:00 PM
Nov 13
Thursday

EPICS Training 2014 - IOC Database Practice

Speaker: Tim Mooney
APS Course
401/A1100 @ 1:00 PM
Nov 13
Thursday

EPICS Training 2014 - Creating Your Own Databases

Speaker: Andrew Johnson
APS Course
401/A1100 @ 2:00 PM
Nov 19
Wednesday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 2:30 PM
Nov 21
Friday

EPICS Training 2014 - Creating IOCs

Speaker: Andrew Johnson
APS Course
401/A1100 @ 2:00 PM
Nov 21
Friday

EPICS Training 2014 - State Notation Language (SNL) Sequencer

Speaker: Andrew Johnson
APS Course
401/A1100 @ 3:00 PM
Nov 21
Friday

EPICS Training 2014 - IOC, Database, and SNL Hands-on Tutorial

Speaker: Andrew Johnson
APS Course
401/A1100 @ 4:00 PM
Dec 17
Wednesday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 2:30 PM

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