Scientific Instrument HED

Proposal preparation for the HED instrument

Frequently asked Questions and Answers

Q: Where can I find the available parameters that HED offers for the current call for proposals?
A: Please refer to this pdf-document.

 

Q: How many experiments will be scheduled?
A: We will schedule up to 10 campaigns (5x12hrs) between August and November 2019. Time to change the setup between those may be only 1-2 days. We encourage isochoric heating, DAC experiments, user-assisted commisioning, and community proposals.

 

Q: What target chambers are available?
A: We offer both interaction chamber 1 (IC) and interaction chamber 2 (IC2). The vacuum in both chambers is oil-free and base operation pressures are around 10-4 mbar (however the chamber can reach lower pressures).
IC1 offers a rectangular multi-purpose chamber with a breadboard. The sample stack in located in the center, featuring a rotation stage, a large hexapod and a sample scanner.  A vertical breadboard has in-vaccum motorozed rails, where detectors and spectrometers can be mounted. The radius of curvature of these rails points towards the interaction point.
IC2 is a chamber dedicated to precision x-ray diffraction. In 2019, it will offer a Diamond Anvil Cell platform. Note that the AGIPD detector is not yet available.

 

Q: What are the x-ray detector specifications?
 

Parameters ePIX100 JUNGFRAU AGIPD-1M*
  (from SLAC) (from PSI) (from DESY)
Sensor thickness/material 300 µm Si 320 µm Si Si
Sensor size 704x758 (35x38mm²) 512x1024 (40x80mm²) 1M
Pixel pitch 50 µm 75 µm 200 µm
Noise (eV) < 280 <450  
Repetition rate (Hz) 10 10 4.5 M
located in/at IC1 IC1 IC2 / detector bench
Number of available Modules 2 4 1

 

* please note that the timeline to integrate the AGIPD detector into the HED instrument does not allow to use this detector in 2019.

 

 

Q: What x-ray photon energies and tunability do you offer?
A: We offer full tunability between 5 and 18 keV with SASE spectrum (0.2% bw). We will have all monochromators available (1eV bandwidth 5-18 keV, and 40 meV bw at 7.49 keV). We offer focused x-rays or collimated x-rays with < 2 µrad divergence and few 100 µm diameter. Currently, we have demonstrated pulse energies in SASE1 of ~1 mJ at < 10 keV, less for higher photon energies. Seeding will not be available in 2019.

 

Q: Does HED offer 25 keV in this call? Is there going to be 3rd harmonic radiation?
A: This call will only offer upt o 18 keV in the fundamental. However, there is always of order 1% 3rd harmonic. 25 keV would be available by using 8.3 keV fudamental, which then needs to be suppressed by means of filters. However, energies exceeding 25 keV are not supported by means of mirrors, focusing capabilities, monochromatization, intensity monitors etc.

 

Q: Will variable pulse duration (2-100 fs) be available for this run?
A: No, we will not offer this for the first half of 2019 to users, this scheme needs development and diagnostics.The linear accelerator is currently running with 250 pC electron bunch charge, and this will probably continue for a while. The SASE intensity is about 1 mJ, and the x-ray pulse length is estimated to be 25 fs maximum. It is probably even a bot shorter, because not the entire electron bunch is lasing. In future (not this call for proposals), it will be possible to have shorter pulses (down to single fs) with less intensity by shortening the electron bunch.

 

Q: Can I bring my own instrumentation (motors, stages, cameras) and will you implement them into the XFEL control system?
A: In general no. In early 2019, we will be fully occupied to commision the baseline instrumentation at HED, and we have no resources to implement additional features. We ask you to check the available equipment. Also, since there are only 1-2 days between two experimental campaigns, there is very little time to work on the mechanical setup. The only possibility is to bring a fully prealigned setup with independent motor controls, which runs stand-alone for your experiment, but this is not perferred as the data is not synchronized with the bunch ID pattern.

The High Energy Density (HED) scientific instrument will be a new, unique platform for experiments combining hard X-ray FEL radiation and the capability to generate matter under extreme conditions of pressure, temperature or electric field using the FEL, high energy optical lasers, or pulsed magnets.

Scientific applications will be studies of matter occurring inside exoplanets, of new extreme-pressure phases and solid-density plasmas, and of structural phase transitions of complex solids in high magnetic fields. In July 2014, the Technical Design report for the HED instrument was published. The HED instrument experiment enclosure construction was completed in July 2014. Construction of the experimental hutches started in late 2015 and continued during 2016. X-ray and optical beamline components commenced in 2016, continued throughout 2017, and we foresee finishing the instrument installation in summer 2018. The first user experiment will start in 2019.