2015-May-22 Diagnostic Development Biweekly Report

(Pavel Evtushenko)

Past weeks works:

1. Mid month activities were centered around the Large Dynamic Range Wire-scanner test in the CEBAF injector. We had a few challenges moving from the lab to the injector, the key problem solved was the semi-tranparent fiber optic cladding. Once this was fixed by adding an opaque sheath, the fiber optic acceptance iris had been open too far - the OTR signal from the wire was washed out from the OTR signal from the beam hitting the dump that was a fraction of a meter away. We had solved all known problems and were scheduled for beam on Friday June 15, unfortunately this opportunity was canceled due to continued Hall B running. We have been promised an opportunity to run in early July prior to the the arrival of the bubble chamber.

2. Hari Areti asked Kevin Jordan to give a talk on transitioning ideas from the lab to industry to the graduate students on May 13. Kevin gave a 1 hour lecture titled "Boron Nitride Nanotube; from the Lab to the Factory - the journey of BNNT LLC", this was an hour long and very well attended and received.

3. Work is continuing to help on the UITF facility, the demolition begins next week. There is still much discussion on the shape of the labyrinth so as to provide sufficient radiation shielding. One conflict is intruding into the space occupied by Physics experimental staging. Yet again more work was done on the budget, Matt Poelker has presented updates to Mont on projected cost increases.

4. Michael Tiefenback have participated in delivering and setting up their "ribbon beam" for Hall-B, focused as nearly as they required, more closely approaching the initial requirements as time passed. The HPS collaboration also learned, in reviewing their specifications that their current density limit which resulted directly in the wide beam requirement was itself in error, and that they were far from target melting limits. They learned that they'd have been in great shape and happy with a 30 micron RMS round spot.

5. Michael Tiefenback provided tentative specs for profile scanner resolution for emittance and Twiss parameter applications. No revisions have been suggested by reviewers. Tentative hardware-based specs for the existing technology wire scanners in the accelerator were also provided, with the immediate objective of providing those executing "hot checkout" with actionable standards for signal quality and noise tolerance, data content and archiving requirements for the "harps" from the control system standpoint, and record-keeping for reference purposes.

6. Michael Tiefenback attended the 6-day IPAC meetings, in the course of which M.T. made agreement with Ed Daly to have a student work with both of them on assessment of the superconducting "hot-wire" anemometer M.T. have been pursuing fitfully over the past 15 yrs.

7. Michael Tiefenback have a student assigned to work with him on "multipass steering in CEBAF," a topic believed to be of great long-term interest both as an operational requirement for keeping the beam close to the intended optical axis in the Spreader/Recombiner areas and as the first example of an alignment tracking and management tool for the accelerator. The highest-pass beam is the most rigid "straight line ruler" we have in the system, and can be used to assess the straightness of the linacs. With proper use, it can also be used to enforce the straightness of the linacs focusing axis. It involves data management and as-built modifications to the beam line model, making the first application of the model to non-ideal issues in the real accelerator.

8. Over the last two weeks we have played main role in commissioning of a new bunch length measurements instrument, which we have jointly designed and built with HZDR. This work was been performed with in a CRADA between HZDR and JLab. The instrument is a Martin-Puplett interferometer. The instrument can operate in vacuum. This makes it fairly unique and allow to remove any atmosphere absorption effects in the far-IR spectra measured by the device, this in tern simplifies the data evaluation significantly, when the instrument is used for bunch length measurements of a very short few 100 fs RMS bunches. The instrument is designed to be suitable for bunch length measurements from a few ps RMS down to well below 50 fs RMS. While commissioning with beam at the ELBE facility at HZDR, we have measured the bunch length in the range from ~ 560 fs through 1.9 ps RMS. These boundaries are however not due to the instrument limitations, but due to the available, during the test, bunch length at the accelerator. Since the design work was performed with in the CRADA, the design of the instrument will be available for JLab.

9. While visiting HZDR, we have worked on further preparations to the laser wire-scanner experiment, which we are preparing there for a beam test. Unfortunately, our progress was impede be a broken component (chiller) of the laser system. Nevertheless, we have had a lot of time to discuss design and modifications of a beam line where the experiment will be setup with mechanical engineering at HZDR. in the mean time we laser system was repaired and is operational again.

10. We have participated in a mini workshop organized at ASML and dedicated to beam diagnostics, required for the machine under design. We have presented our designed, developments and considerations made at JLab for the project.

11. In the period prior to HZDR visit a significant effort was made for final preparations of the beam test of a Large Dynamic Range wire-scanner, which was taken place at CEBAF injector. One specific aspect of the test was that it had to be performed with PI absent from the lab (on HZDR visit) also participating in the test remotely as much as the time allowed. It was very encouraging to see that all new diagnostic equipment could be operated without IP on its first beam test. Joe Gubeli and Kevin Jordan were executing the test, and have made significant progress in the little beam time available. We will be making further improvement to the setup in the next month before one more opportunity for beam test in the beginning of July.

New future plans:

Over the next two weeks Kevin Jordan will be spending time on UITF controls and diagnostics hardware, as well as attending MEIC design meetings. He also will spend a few hour on the Accelerator Stewardship program for Andrew & Hari.

Michael Tiefenback be following up on these last two items and on MEIC work. Mike hope to revisit the issue of active noise cancellation in the cryomodules, as well, but this will take more time to convince people of this than of the parallel utility of breaking the construction symmetry of the cryomodules to de-Q the acoustic resonances. Both of these would be marvelously useful contributions to our SRF technology, but appear to be outside the "field of view" of present participants.