ERL2011 - List of Authors (Smedley, J.)

Paper

Title

Page

WG1003

First Results of the SRF Gun Development for the BERLinPro ERL Project at HZB

T. Quast, W. Anders, R. Barday, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, S.G. Schubert, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
I. Will
MBI, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung und Land Berlin. The work on the Pb cathode film is supported by EuCARD Grant Agreement No. 227579.
For the energy recovery linac (BERLinPro) at the Helmholtz-Zentrum-Berlin (HZB) a high brightness, high average current electron source is to be developed. As a first step an all superconducting radio-frequency (SRF) photoinjector is now in operation. The aim is to demonstrate electron beam produced from a Nb 1.6 cell superconducting gun with a Pb cathode coated on the cavity back wall. The setup of the source and first results from beam measurements are presented. An outlook on the final SRF photoinjector and its drive laser will be given.

Slides WG1003 [2.844 MB]

WG1016

Progress at BNL Towards Development of Efficient, Robust Photocathodes for High Average Current Operation

T. Rao, S.A. Belomestnykh, I. Ben-Zvi, X. Chang, J. Smedley, E. Wang, Q. Wu
BNL, Upton, Long Island, New York, USA
X. Liang, M. Ruiz-Osés, T. Xin
Stony Brook University, Stony Brook, USA
R.R. Mammei, J.L. McCarter, M. Poelker, R. Suleiman
JLAB, Newport News, Virginia, USA
E.M. Muller
SBU, Stony Brook, New York, USA

The photocathode research at BNL is proceeding along two parallel paths, characterizing the cathodes as they are being fabricated and testing them in a variety of guns. Using modern surface science techniques such as X-Ray Reflection (XRR), X-Ray Diffraction (XRD) and X-Ray photoemission spectroscopy (XPS), we have investigated Sb and K-Cs-Sb layers as a function of the deposition technique, substrate material and deposition recipes. The talk will cover the latest results of these investigations. Cathode insertion section for the 112 MHz SRF gun is being designed for testing multialkali and diamond secondary emission cathodes. The status of the designs will also be presented. In addition, the multialkali cathode, fabricated at BNL and transported to JLab, has been tested for high current operation in a DC injector at JLab. The performance of this cathode when irradiated 440 nm and 532 nm radiation, under different bias voltages and average currents will be presented.

Slides WG1016 [4.189 MB]

PSP019

Charge Lifetime, Emittance, and Surface Analysis Studies of K2CsSb Photocathode in a JLab DC High Voltage Gun

133

J.L. McCarter
UVa, Charlottesville, Virginia, USA
R.R. Mammei, M. Poelker, R. Suleiman
JLAB, Newport News, Virginia, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: DOE Grant # DE-FG02-97ER41025
For the past year, BNL and JLab groups have been collaborating to study the characteristics of K2CsSb photocathodes inside a DC high voltage photogun. Although the first set of runs at 1 mA and at 100 kV bias voltage indicated disappointing charge lifetime, comparable to values obtained with GaAs photocathodes, subsequent measurements indicate that both the QE and charge life time increased significantly. This improvement could be attributed to the change in the chemical composition of the cathode due to UV irradiation. The charge life time measurements do not indicate any QE decay for currents of 10 mA over 350 micron FWHM spot, slight decay at 16 mA and significant decay at 20 mA for this spot size. When the spot size is increased to 850 micron, the lifetime at 20 mA increased significantly, implying local heating due to high laser intensity. Additional measurements with laser alone, without the HV, support this argument. These results as well as emittance and surface science measurements will be presented.