Performance Metrics: User Time for FY14 - Part 1

Performance Metrics: User Time ("Over-compressed, High Charge")

Experiment: E-201 DIELECTRIC WAKEFIELD ACCELERATION

Date: 10/28/2013

Summary from User:

Run went about as well as could be expected without beam marks on the screens. It has traditionally been very difficult to align the system without a known good orbit before attempting. All motors, cameras and actuators are working.

Experiment: E-210 TROJAN HORSE PLASMA WAKEFILED ACCELERATION

Date: 10/31/2013

Summary from User:

We met the goal for this initial check-out of our apparatus and observed the position of the beam through Optical Transition Radiation (OTR). On our next access we will install a photodiode to detect this OTR which is necessary for the coarse timing of the electron beam to the laser beam.

Experiment: E-201 DIELECTRIC WAKEFIELD ACCELERATION

Date: 10/31/2013

Summary from User:

Run went about as well as could be expected without beam marks on the screens. It has traditionally been very difficult to align the system without a known good orbit before attempting. All motors, cameras and actuators are working.

Experiment: E-201 DIELECTRIC WAKEFIELD ACCELERATION

Date: 11/1/2013

Summary from User:

Two different beam energy spectrums were taken at different relative linac phases, using the tubes, and will be analyzed to give more information about the phasing of the linac to help improve future performance. This data can also be used to improve on previous results looking for energy loss in dielectric structures indicative of GV/m wakefields.

Experiment: E-211 CERN BEAM BASED ALIGNMENT

Date: 11/3/2013

Summary from User:

Investigated ways to automatically reduce the linac charge. Measured nominal response and low-charge response. Verified that global orbit correction (still) works well. First Wake field steering attemps did induce transverse tails. Will investigate further where the problem lies.

Experiment: E-211 CERN BEAM BASED ALIGNMENT

Date: 11/4/2013

Summary from User:

Measured nominal response and low-charge response for LI02-LI07. Investigated svd_cuts versus corrector strength. More correctors per sector may be needed to improve performance.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 11/5/2013

Summary from User:

Tested the updated E200 data acquisition and data review tools successfully. Promising data acquired to test single-shot emittance diagnostic algorithms.

Experiment: E-211 CERN BEAM BASED ALIGNMENT

Date: 11/7/2013

Summary from User:

Benchmarked the wakefield steering scheme on LI02 and LI03. Performed parameter 2D scan, located minimum and measured emittance.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 11/8/2013

Summary from User:

Checked out CMOS with temporary server solution. Worked well, however, system went down, and need expert help to revive. Successfully performed QS scans for emittance measurements.

Experiment: E-213 RESISTIVE SAMPLES

Date: 11/9/2013

Summary from User:

Different resistive structures were used to evaluate the damage due to a longer electron bunch with double peak structure. Electron microscope evaluation to be done after removal.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 11/9/2013

Summary from User:

We finished the experimental measurements that we set out to perform. We performed a tomography of the longitudinal phase space of the beam.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 11/10/2013

Summary from User:

We tested all our OTR beam diagnostics along the FACET experimental area. We continued our study of the longitudinal phase space of the electron beam using two different methods.

Experiment: E-201 DIELECTRIC WAKEFIELD ACCELERATION

Date: 11/11/2013

Summary from User:

E201 generated narrowband THz radiation through sub-mm capillary structures and attempted to image this radiation with a pyro-electric detector array but found minimal success on this initial run.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 11/16/2013

Summary from User:

We studied the alignment and performance of both CHER systems. The CHER_NEAR alignment was studied. For CHER_FAR dispersion and vignetting data was logged, to be analyzed. By eyeballing both systems are in a state ready to do plasma experiments, however, some fine adjustment are desirable. The CMOS system is still hard to work with, and requires significant of manual intervention.

Experiment: E-201 DIELECTRIC WAKEFIELD ACCELERATION

Date: 11/18/2013

Summary from User:

E201 generated narrowband THz radiation through sub-mm capillary structures and attempted to image this radiation with a pyro-electric detector array but found minimal success on this initial run. E201 attempted to use the emitted coherent Cerenkov radiation from the dielectric structures for imaging a leaf sample. We first used coherent transition radiation to test that the imaging diagnostic (pyrocam) was functioning properly. We were able to image some features of the sample, however further analysis is still needed.

Experiment: E-210 TROJAN HORSE WAKEFIELD ACCELERATION

Date: 11/18/2013

Summary from User:

OTR image of at the EOS cube. Actuator motor is at 21.3 mm. Charge is 2E10, polarizer is installed (although still needs fine alignment). Polarizer doesn't block field of view, now can see both OTR and EOS laser signal. Also looked at OTR using photodiode borrowed from E200. No signal observed on diode with OTR screen inserted.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 11/22/2013

Summary from User:

We have identified the best strategy to perform a tomographic reconstruction of the longitudinal phase space in a time-efficient manner, allowing to considerably reduce the sensitivity of the measure to the drift of the transverse deflecting cavity and of the machine.

Experiment: E-201 DIELECTRIC WAKEFIELD ACCELERATION

Date: 11/23/2013

Summary from User:

We established the background radiation (IR to THz) at FACET which is co-propagating with the beam and collected by parabolic mirror is much greater than expected. The background as seen by the camera drove the camera to half the full dynamic range. When a beam imaging foil was inserted into the beam path, at the location of smallest beam size, the radiation collected and imaged by the camera completely saturated the viewable area of the camera (1.54 cm^2 viewable area), with the camera not at the focus of the OAP. The pyrocam has a Silicon beam splitter which blocks visible light.

Experiment: E-209 SELF-MODULATION OF LONG BUNCHES IN DENSE PLASMA

Date: 11/23/2013

Summary from User:

Need more analysis and understanding of the results. Preliminary results seem good, i.e., we can measure the bunch radial variation using CTR.

Experiment: E-210 TROJAN HORSE WAKEFIELD ACCELERATION

Date: 11/26/2013

Summary from User:

We did not see the ladder moving cross the field of view as usual. We can barely see the OTR signal on the CCD. We had orbit steered and did not observe CCD intensity enhancement. Possibly the camera needs to be replaced. We also did not see the OTR signal from photodiode. The actuator position is 21.3mm. The OTR signal is very dim on the screen.

Experiment: E-203 SMITH PURCELL LONGITUDINAL BUNCH MEASUREMENTS

Date: 11/26/2013

Summary from User:

We successfully tested our wire-scanner. The signal to noise ratio was lower than expected but we clearly identified the position of the beam with an accuracy of about than 100um (as required). Further analysis to follow.

Experiment: E-203 SMITH PURCELL LONGITUDINAL BUNCH MEASUREMENTS

Date: 11/29/2013

Summary from User:

We managed to successfully test our equipment (wire-scanner, motor control system,...) unfortunately the beam conditions did not allow us to perform the measurements we wanted to do.

Experiment: E-203 SMITH PURCELL LONGITUDINAL BUNCH MEASUREMENTS

Date: 12/01/2013

Summary from User:

Smith-Purcell measurements were successfully done on two beam configurations: one without the notch collimator, and one with the notch collimator inserted. The background was low enough to allow data taking. The reconstructed profiles will be compared with each other and with TCAV measurements.

Experiment: E-210 TROJAN HORSE WAKEFIELD ACCELERATION

Date: 12/08/2013

Summary from User:

Electron beam arrival time was detected on the SiPMT photodiode installed at the EOS set-up.It can be used for the coarse (100s picoseconds) timing of the laser to the electron beam to get us a starting point for the EOS scan for fine (100s femtosecond) timing.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/09/2013

Summary from User:

We realized the first automated measurement of the longitudinal phase space of the electron beam.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/10/2013

Summary from User:

We measured a highly compressed beam.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/13/2013

Summary from User:

We re-did the cherenkov vignetting scans after fixing the aperture. By eyeballing we did not see significant vignetting. Will analyze further, but it is positive that CHER_FAR is now good to go for plasma experiments from this perspective.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/15/2013

Summary from User:

The oven and electron beam are both in a good state. The laser is in a good state but the gold IP mirror tilt motor is not working. The notch and jaw motors are not as usable as they should be.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/16/2013

Summary from User:

Acceleration of the witness electron bunch by 2 GeV was observed for the first time this run, with very good performance of the ionizing laser. The longitudinal phase space was successfully characterized with the tomographic slit scan technique, allowing a better understanding of how the 2-bunch structure is created.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/17/2013

Summary from User:

The uncertainty of seeing two bunches with the TCAV makes it difficult to know if one or two bunches was being inserted into the plasma. The uncertainty in the delivered beam means that any plasma interaction achieved would also not be well-understood. It was decided to return the program to ops in order to improve the beam and try again tomorrow.

Experiment: E-200 PLASMA WAKEFIELD ACCELERATION

Date: 12/20/2013

Summary from User:

The goal for this shift was to characterize the beam acceleration at plasma density of 5e16/cm³. We performed measurements with the laser on and off. We saw evidence for the energy acceleration approximately 3 GeV. We translated the laser path in x to vary the plasma interaction and estimate the diameter of the plasma column involved in the interaction (1.2 mm).