Ultrathin Gas Jet for NonInvasive Beam Halo Measurement

Ultra-thin Gas Jet for Non-Invasive Beam Halo Measurement Adam Jeff CERN & University of Liverpool Workshop on Beam Halo Monitoring 19 th September 2014

adam. jeff@cern. ch Contents • • The CLIC Drive Beam Jet monitor principle Jet generation & shaping Test Stand @ the Cockcroft Institute Experimental Results Quantum focusing Prospects (sieve)

1 / 17 The CLIC Drive Beam adam. jeff@cern. ch Beam Energy Beam Current Pulse Length to 2. 4 Ge. V 4. 2 A 140 μs

2 / 17 adam. jeff@cern. ch Principle of the gas jet monitor • Generate thin atom gas curtain, • Ionize atoms with primary particle beam, • Extract ions via electric field, • Monitor on MCP, P screen. Y. Hashimoto et al. , Proc. Part. Acc. Conf. , Chicago (2001)

adam. jeff@cern. ch Test Setup @ Cockcroft Institute Thanks to M. Putignano 3 / 17

adam. jeff@cern. ch Test Setup @ Cockcroft Institute 4 / 17

adam. jeff@cern. ch Test Setup @ Cockcroft Institute 5 / 17 e- beam Gas Jet

adam. jeff@cern. ch Test Setup @ Cockcroft Institute Residual Gas Ions Gas Jet Ions E Gas Jet e- 6 / 17

adam. jeff@cern. ch Test Setup @ Cockcroft Institute 5 / 17

7 / 17 Vacuum Effects adam. jeff@cern. ch V. Tzoganis, A. Jeff, C. Welsch , “Gas dynamics considerations in a non-invasive profile monitor for charged particle beams”, Vacuum (2014), dx. doi. org/10. 1016/j. vacuum. 2014. 07. 009

8 / 17 Pulsed Jet adam. jeff@cern. ch Valve Control Jet Brightness Chamber Pressure

9 / 17 Gas Jet Scanner adam. jeff@cern. ch Shaping of gas curtain possible through sole manipulation of Pressure and Temperature of Gas Reservoir. 1 order of magnitude density difference between core and side strands M. Putignano, C. P. Welsch, “Numerical study on the generation of a planar supersonic gas-jet”, NIM A 667 (2012)

adam. jeff@cern. ch Gas Jet Scanner 10 / 17 • halo beam halo E

11 / 17 Gas Jet Scanner adam. jeff@cern. ch • Alternative Solution: Gas Jet Scanner – Generate a thin pencil jet and scan it through the beam – Like a wire scanner but non-interceptive – Still collect ions but position not important: not affected by space charge – Slow scan through halo region, fast through main beam – Need a way to generate a thin jet…

12 / 17 adam. jeff@cern. ch Matter-Wave Focusing for a Thin Neutral Jet Smallest zone 100 nm FWHM at focus 2μm ! T. Reisinger, S. Eder, M. M. Greve, H. I. Smith, B. Holst, “Free-standing silicon nitride zoneplates for neutral-helium microscopy”, Microelectronic Engineering 87 (2010)

13 / 17 Fresnel Zone Plates • The path difference between each successive light ring is equal to 1 wavelength (at the focal point) constructive interference. • Each zone is equal in area • Focal spot size is roughly the width of the narrowest (outer) zone • Compared to traditional lens: no spherical aberration, large chromatic aberration adam. jeff@cern. ch De. Broglie wavelength ≈ 0. 05 nm for room temperature Helium radius of outer zone width of outer zone Focal length of zone plate Resolution ≈ width of smallest zone (ignoring chromatic effects)

14 / 17 Photon Sieve replaces clear zones of an FZP with a series of holes adam. jeff@cern. ch Photon Sieves + Sharper focusing - Lower transmission + Easier to manufacture Apodised Photon Sieve reduces higher order diffraction, increases central maximum L. Kipp et al, “Sharper images by focusing soft X-rays with photon sieves”, Nature 414 (2001)

adam. jeff@cern. ch ZEMAX Simulations 15 / 17

adam. jeff@cern. ch The Atomic Sieve 16 / 17 The Atomic Sieve

17 / 17 Conclusions • The test setup at the Cockcroft Institute has demonstrated reliable gas jet operation, and can be used for profile measurement in both continuous and pulsed mode. • Thanks to efficient dumping of the jet and differential pumping in the jet generator, the effect on the beam vacuum system is small. • A split jet can be generated for halo imaging • Additional discrimination would be needed to achieve high DR adam. jeff@cern. ch • An alternative solution is a gas jet scanner • A focusing method based on the de. Broglie wavelength of the neutral gas atoms will be tested. • The ‘atomic sieve’ is under production and will be tested later this year.

Thank you for your Attention Adam Jeff 1, 2, Barbara Holzer 1, Thibaut Lefèvre 1, Vasilis Tzoganis 2, 3, Carsten Welsch 2, 3 and Hao Zhang 2, 3 1 CERN 2 University of Liverpool 3 Cockcroft Institute Workshop on Beam Halo Monitoring 19 th September 2014