Brief overall description of the Task WP12.5 Photocathodes

1. Brief overall description of the Task WP12.5 Photocathodes for the reporting period: 1.05.2013 – 30.04.2014

2. WP12.5 Brief overall description Fields of interest: • Evaluate Pb photocathode deposition for improved performance of SRF guns • Characterise and optimise performance of Diamond Amplifier Cathode solutions for SRF guns • Material R&D for advanced photo cathodes for NC RF guns Actions and institutions:

3. WP12.5 Brief overall description Milestones Deliverables

4. WP12.5 Brief overall description Kick off Meeting Task 12.5 on RF Photocathodes at HZBon 12.07.2013 http://eucard2.web.cern.ch/content/work-packages

5. Capabilities WP12.5 Brief overall description

6. WP12.5 Brief overall description Helmholtz Zentrum Dresden Rossendorf • The goal of our task is to study next generation photocathodes deliveringhigh brightness, high average current electron beams. We want to investigate wanted and unwanted beam properties and work on the integration of the photocathode into the SRF gun enviroment. Candidatesfor next generation cathodes include Diamond Amplifier Cathodes (DAC)and Diamond Field Emitte Arrays (DFEA). • Work on Subtask 12.5.1 Pb photocathode depositionHZDR fabricated, polished and shiped four Nb plugsfor Pb depositionto NCBJ Swierk. The plugs are deposited there with 2µm Pb. Nextstep is laser cleaning (needs help of NCBJ)and quantum efficiencymeasurement at 252 nm in thephotocathode preparation system at HZDR.(work for Delivery D12.9 in 3/2016) • Work on Subtask 12.5.2 Diamond amplifier cathode development. Contact to BNL on requirements for integration in SRF gun.

7. Helmholtz Zentrum Berlin WP12.5 Brief overall description FieldEmissionLaboratory:Test dark current emission from substrates and cathode films under high electric DC fields • Currentmeasurement • Image oftheemitters on theviewscreen • Constant gap d=0.4 mm • Gradient canbechangedbycontrolling • biasvoltage (Umax=10 kV) Setup complete and under vacuum, first tests with diamond field emitter array cathodes (collaboration University Vanderbildt) and Mo substrates. Next step is commissioning with 5 kV DC voltage, then increasing up to 10 kV voltage (at 0.4 mm gap  25 MV/m).

8. WP12.5 Brief overall description DeutschesElektronen Synchrotron Status of the SRF-gun cavity with plug at DESY Gasket made of In foil Further information will be provided by W Grabowski of NCBJ Swierk see the further presentation

9. Science & Technology Facilities Council, Cockroft Inst. Analyser X-ray Gun AFM WP12.5 Brief overall description LEED UHV Vacuum System Surface Analysis/Preparation Installation (SAPI) • A multi-chamber ultra-high vacuum system has been constructed and equipped with a number of surface analysis techniques. • The commissioning of the SAPI system is a key milestone in this sub-task and has been reported as CERN-ACC-2014-0039 • Work is now progressing on the investigation of a series of alternative metal photocathode materials using the facilities at Daresbury. see the further presentation

10. Narodowe Centrum Badań Jądrowych, Świerk WP12.5 Brief overall description UHV arc deposition devices Pb/Nb layers post- processing Surface analysis; photocathode tests IBIS rod plasma injector SEM laboratory Short arc device Filtered UHV arc system Probe heater for vacuum annealling Photocathode diagnostic stand – under construction

11. WP12.5 Brief overall description Thank you for your attention !