| Day : 1. Monday (5)|
|3/1/2010 1:30 PM||2:00 PM||Soren Prestemon, LBNL||Alexander|
|3/1/2010 1:30 PM||4:00 PM||Alexander|
|3/1/2010 2:00 PM||2:30 PM||Alexander Temnykh, Cornell ||Alexander|
|3/1/2010 2:30 PM||3:00 PM||Heinz-Dieter Nuhn , SLAC||Alexander|
|3/1/2010 3:00 PM||4:00 PM||All||Alexander|
| Day : 2. Tuesday (7)|
|3/2/2010 1:30 PM||04:00 PM||Alexander|
|3/2/2010 1:30 PM||2:00 PM||Hugh Philipp, Cornell||Alexander|
|3/2/2010 2:00 PM||2:30 PM||Dionisio Doering, LBNL ||Alexander|
LBNL has developed an X-ray camera using a custom CCD sensor and custom ADC/readout IC. The first version of CCD sensor used for proof of principle is 480 x 480 pixels. The pixel size is 30x30um. This device is back illuminated, 200 um thick and fully depleted. Its efficiency for X-ray for energies up to about 8 keV is close to 100% and it covers the needs of the Advanced Light Source as a soft X-ray facility. The CCD has 96 outputs that allow the camera to run up to 200 fps. In order to digitize the data from the sensor, we developed a custom ADC/readout ASIC called FCRIC. This chip has 16 inputs and 4 digital outputs. Each output sends the data from 4 inputs serially using LVDS logic. The chip besides digitizing the data in 15 bits range has 3 gain selections that automatically change to accommodate low and high input pulses. It also performs correlated double sampling. These ICs are described in . The first prototype has been used at the ALS and it showed promising results. In order to be able to better fit this camera into new experiments a new camera head was designed. This is called c(compact)FCCD. This new camera uses the same sensor and ADC/readout chip but it fits in a 2.5inch cube. The camera will be used in an experiment on Hutch 2 at LCLS later in 2010.
The forecasts for future light sources needs indicate that faster and bigger (more pixels) sensor will be needed. LBNL is researching new technologies to solve this new requirement. Among several options SOI (Silicon On Insulator) has been studied under Laboratory Directed R&D funds. Some initial good results have been presented. Currently we are working on a X-ray sensor called femtopix. This is a gated chip that performs correlated double sampling. The goal of this chip is to run at 4000fps allowing the study of a femto sliced bunches while avoiding the front end to be swamped by the back ground radiation by gating the input.
The presentation concludes stating the most of the current sensor (not limited to the ones developed at the lab) do not perform image processing in hardware and in real time. They usually send raw data to a storage system. This solution works for the present systems but as we progress into the future where the sensors will run as fast as 100k fps this will not be a reasonable solution because the data through put will too big and the storage systems will also be too big. For this reason research on adding intelligence to these cameras by adding more logic to the pixels and to the readout systems through the use of FPGA is currently taking place at the LBNL. These new sensors and new image processing algorithms will be part of the solution to develop the cameras that will meet the need of the future light sources in our opinion.
|3/2/2010 2:30 PM||3:00 PM||Daniel Rolles, CFEL, Universität Hamburg||Alexander|
Daniel Rolles: pnCCD and active pixel sensor development at HLL
In order to meet the X-ray detector needs of fourth generation light sources, especially FELs, the Max Planck Semiconductor Laboratory (HPI Halbleiterlabor) in Munich has developed a dedicated single photon counting 1024x1024 pixel pnCCD X-ray imaging detector with an active area of 7.8 x 7.4 cm² and a frame rate up to 200 Hz. It has an operating range between approx. 0.05 and 25 keV with a quantum efficiency of >0.8 for 0.3-12 keV and a typical read-out noise of 2.5 electrons (rms) at an operating temperature of -50°C. At a pixel size of 75x75 m² and a fully depleted silicon thickness of 450 m, each pixel has a charge handling capacity of approx. 5x105 electrons (equivalent to 10³ photons at 2 keV). A 2.4 mm center hole in the detector allows the direct FEL beam to pass through the detector so it can be mounted in a forward scattering geometry.
The detector was successfully commissioned and employed for first user experiments in the CFEL-ASG MultiPurpose (CAMP) chamber at LCLS in November/December 2009. In the course of the experiments, X-ray fluorescence of highly charged rare-gas atoms was detected on the pnCCD, taking advantage of the intrinsic photon energy resolution of approx. 50 eV at 800 eV incident photon energy. Additionally, X-ray scattering patterns of rare-gas clusters as well as biological nano-crystals and viruses were recorded for photon energies between 1.5 and 2 keV. Further experiments with the pnCCD detectors in the CAMP chamber will be carried out at the AMO beamline of LCLS in May-July 2010 and in early 2011.
Simultaneously, a 2-Megapixel detector consisting of four pnCCD quadrants with a total active area 15x15 cm² and a variable hole size is under development, aiming at having the detector operational in 2012/2013.
In order to allow single-shot X-ray imaging at superconducting FELs such as the European XFEL operated in the burst mode, HLL is currently developing a 1-Megapixel DePFET active pixel sensor detector, with a frame rate of 1-5 MHz. It will have hexagonal pixels with a pitch of ~204 x 236 m², a dynamic range of > 10.000 photons (@1keV) per pixel per pulse and an electronic noise of < 25 electrons (rms) at an operating temperature of -10°C. This development is intended to be operational for the start of the first user experiments at the European XFEL.
|3/2/2010 3:00 PM||4:00 PM||All||Alexander|
|3/2/2010 4:30 PM||5:00 pm||Jacobsen||SSRL Conference room (Bldg. 137W Room 322)|
|3/2/2010 5:00 PM||6:00 pm||All + Chris Jacobsen (leader)||SSRL Conference room (Bldg. 137W Room 322)|
| Day : 4. Thursday (4)|
|3/4/2010 9:00 AM||09:30 AM||Michael Klopf, Jlab||Alexander|
Outline of the proposed JLAMP VUV/soft X-ray FEL
and the challenges for the photon beamlines and optics
J. Michael Klopf
Jefferson Lab, FEL Division
An overview of the design concept and technical parameters of the proposed JLAMP VUV/soft X-ray FEL will be presented. The design provides for a wide range of photon energies, from 10 eV to 100 eV in the fundamental (harmonics over 500 eV), with very high peak and average brightness. The extremely high brightness of the photon pulses combined with the ultrashort (~ 100 fs FWHM) pulsewidth present particular challenges for the beamline optics. It becomes necessary to consider not only the damage threshold due to thermal loading, but also the ablation threshold as a result of the high peak power of the ultrashort pulses. The beamline optics for JLAMP must withstand damage and operate over a very wide spectral range for the users. For many spectroscopic experiments, it will be necessary to narrow the spectral bandwidth of the pulses, while time resolved measurements will call for minimum pulsewidth with little or no spectral conditioning. To accommodate these wide ranging requirements, the JLAMP beamline is designed with two branches optimized for time resolved or spectrally resolved measurements. A third beamline branch with normal incidence optics will operate at photon energies below 30 eV. The design concept for all of these beamline branches and their associated optics will be presented along with the challenges we foresee in realizing the design goals. Also, similar to the FLASH design, the JLAMP design incorporates a Far/Mid Infrared undulator using the same electron beam as the VUV/soft X-ray source. This provides a perfectly synchronous source at low photon energies ideal for many pump-probe experiments. The beamline concept for transporting and controlling the relative delay of these FIR/MIR pulses will also be discussed.
|3/4/2010 9:30 AM||10:00 AM||Don Bilderback, Cornell||Alexander|
Nanoprobe Beamline for the Cornell ERL
Don Bilderback, Cornell University
Cornell University is soon planning to submit a 5 GeV proposal for an Energy Recovery Linac to the National Science Foundation. One of the 14 planned x-ray beam lines will be one for x-ray science featuring coherent x-rays beams of 1 to 10 nm spot size between 1 to 20 keV.
A Delta style undulator of 3 to 5 meter length will provide the x-rays for the sector. The main challenge at this point will be to provide x-ray optics that is capable of making such small beams. We currently don’t have optics that can reach this size scale, but are factors of 10 to 20 away with current technologies. Candidate optics for this energy regime includes Laue lenses, refractive optics, zone plates, KB and multilayer mirrors.
The method of this beamline is to make a small beam and, with it, to scan the sample with a raster scan. What is required to make scanning images is an ultra-high brightness, high-rep rate source to have enough flux in a few nm square area for rapid x-ray fluorescence or EXAFs experiments while minimally disturbing the sample.
This beamline won’t compete with the 0.1 nm size of electron probes on thin samples or surfaces, but could do very novel and leading-edge work in buried layer structures, in diamond cells, nasty chemical cells, etc.
Two applications immediately come to mind: 1) Perform experiments on a single atom (not possible with x-rays now) or in clusters in a narrow line-width buried transistor structure. Atoms will be located in 2d with scanning fluorescence images. The electrical activity (active or inactive donor) will be determined by a near-edge spectroscopy. This may be useful diagnostic tool when the smallest electronic structures require the highest dopant densities lead to the formation of inactive clusters when the dopant density is increased too far. 2)To see single high-z atoms moving in-situ in a catalyst nanoparticle during a chemical reaction.
Several groups are on a path to achieve a small nanofocused x-ray beam. The
NSLSII is on this path with Laue lenses hoping to deliver 1E10 x-rays/sec into a 1 nm focus. The scaling for the Cornell ERL could provide 1 to 2 orders of magnitude of more flux in same spot size. [Even at these high fluences, we estimate that we will only singly ionize an Erbium dopant atom in a silicon single crystal with a temperature rise of order one degree from beam heating.]
With an ERL, we possibly could have high-z fluorescent intensities up to 1E6 x-rays/sec into a 2*pi detector for imaging, EXAFS, etc. The background from Compton scattering in silicon would be about equal to the fluorescent count rate. The result is an opportunity to provide some rapid, near real-time images of moving atoms.
As part of the beamline development, we are also interested in creating a confocal x-ray microscope where we can isolate x-ray signals to a volume of 1 nm **3. We have started to microfabricate a radial Soller slit with 1 micron openings to achieve a roughly 1 micron depth resolution behind a glass capillary focusing optic. When we have first results, we plan to scale this type of optic down to nm resolution.
One unresolved issue is whether or not to create a secondary focal spot where a pinhole can be placed in order to remove the effects of electron source motion before demagnifiying to nm beam size further downstream. The NSLSII Nanoprobe beamline is taking this approach. If you have the highest confidence that the source will be stable enough, then you might skip this step and directly proceed to the ultimate nm spot size, thus saving length in the beam line. More design work is needed to adequately resolve this issue.
|3/4/2010 11:00 AM||11:30 AM||Joel Brock, Cornell||Alexander|
|3/4/2010 11:30 AM||12:00 PM||Michael Green, U. Wisconsin (postdeadline comment)||Alexander|
| Day : 5. Friday (1)|
|3/5/2010 1:30 PM||02:00 PM||Panofsky Auditorium|