Plasma Wakefield Acceleration and a possible eP scattering Experiment MPP Retreat January 21, 2014 Allen Caldwell

Use an existing proton bunch (e.g., SPS) to generate plasma wave. First, proton bunch needs to be modulated. Simulation courtesy Wei Lu, Tsinghua University Allen Caldwell

Simulations indicate can capture up to 40% of electron bunch this way. Electron injection needs to occur after modulation has completed. Investigating ‘side injection’ Simulations indicate can capture up to 40% of electron bunch this way. Simulation: Konstantin Lotov, Budker Institute Allen Caldwell

Outlook Long term prospects for modulated proton bunch intriguing: Electron energy gain simulation of existing LHC bunch in plasma with trailing electrons … A. Caldwell, K. V. Lotov, Phys. Plasmas 18, 13101 (2011) Miracle: no guiding magnetic fields necessary ! But – luminosity will be big issue ! Allen Caldwell

AWAKE Experiment at CERN Allen Caldwell

APPROVED Project Structure Allen Caldwell AWAKE Collaboration Spokesperson: Allen Caldwell Deputy: Matthew Wing Experiment Coordinator Patric Muggli Simulation/Theory Coordinator Konstantin Lotov Accelerator & Infrastructure Coordinator Edda Gschwendtner (CERN Project leader) Project Management WP Edda Gschwendtner RP and Safety WP Helmut Vincke Metal Vapor Plasma Cell WP Erdem Öz Simulations WP Konstantin Lotov APPROVED Experimental Area WP Edda Gschwendtner Helicon Plasma Cell WP Olaf Grülke SPS Beam WP TBD Pulsed Discharge Plasma Cell WP Nelson Lopes Interface p/e/laser/plasma WP Edda Gschwendtner Beam-Line WP Chiara Bracco Layout, Integration Coordination WP Ans Pardons Electron Spectrometer WP Simon Jolly e—gun– collaboration with institutes… Practical issues are needed! Proton Beam-Line WP Chiara Bracco Optical Diagnostics WP Roxana Tarkeshian Secondary Beam Diagnostics WP TBD General Services WP TBD Electron Beam-Line WP Chiara Bracco Electron Source WP Tim Noakes Allen Caldwell

A possible future electron-positron collider based on proton driven plasma wakefield acceleration and/or Electron-proton collider based in PDPWA Allen Caldwell

HERA Kinematics Ee=27.5 GeV EP=920 GeV s=(k+P)2 = (320 GeV)2  Transverse distance scale:  Allen Caldwell Future ? A. Caldwell Max-Placnk-Institut für Physik

{ Structure Functions k k’ ‘structure functions’ Transverse resolution What we measure Parton momentum (fraction of proton momentum) Inelasticity Allen Caldwell A. Caldwell Max-Placnk-Institut für Physik

The rise of F2 with decreasing x is strongly dependent on Q2. First HERA discovery Small-x F2 x- The rise of F2 with decreasing x is strongly dependent on Q2. Or, the proton, viewed with a fine probe, is full of quarks, antiquarks and gluons ! Increasing energy shorter time fluctuations Allen Caldwell A. Caldwell Max-Placnk-Institut für Physik

The rise at small x Q=1 GeV corresponds to about 0.2 fm Parametrize: Below Q2 0.5 GeV2, see same x (energy) dependence as observed in hadron-hadron scattering Q=1 GeV corresponds to about 0.2 fm Transition region Allen Caldwell A. Caldwell Max-Placnk-Institut für Physik

Electron Proton Scattering in the Proton Rest Frame So, small-x means long-lived photon fluctuations (not proton structure) Allen Caldwell A. Caldwell Max-Placnk-Institut für Physik

Small-x, small Q2 Larger-x, larger Q2 Allen Caldwell A. Caldwell Max-Placnk-Institut für Physik

Can we probe this behavior at higher energies ? A. Caldwell arXiv:0802.0769 Slope of the cross section with l increases with Q2. Extrapolation of the cross section with fixed slope. Can we probe this behavior at higher energies ?

Distribution of ‘wee’ partons not understood Fundamental aspect of nature Theoretical problem, but more data can help Collider design issues based on proton-driven plasma wakefield acceleration G. Xia et al.,http://dx.doi.org/10.1016/j.nima.2013.11.006 Allen Caldwell

Allen Caldwell s = 28 sHERA

Optimized Detector together with higher energy could bring big step in understanding Electron Hemisphere Allen Caldwell