For discussion of experiments with bent crystals at

For discussion of experiments with bent crystals at SLAC based on discussions in the SLAC Crystal task force John Amann, Alex Chao, Lew Keller, Tom Markiewicz, Bob Noble, Marco Oriunno, Shilun Pei, Andrei Seryi, Jeff Smith, Jim Spencer, Gennady Stupakov, Uli Wienands with significant contributions from Crystal collaboration, represented by Ralph Assmann, Davide Bolognini, Yury Chesnokov, Angelika Drees, Vladimir Maisheev, Nikolai Mokhov, Steve Peggs, Michela Prest, Guillaume Robert-Demolaize, Walter Scandale, Igor Yazynin, et al more info: http: //indico. fnal. gov/category. Display. py? categ. Id=106 (SLAC CRYSTAL working group meetings) Slides in this talk are from Walter Scandale Marco Oriunno Jim Spencer Yury Chesnokov Gennady Stupakov July 25, 2008, Crystal experiments at SLAC

Plan * Motivation – Hadron machine collimation system – Linear collider collimation system – Photon source * Highlights of the phenomena – Channeling – Volume reflection (VR) – Radiation during volume reflection * What is done in the world – Channeling experiments – Start of VR exploration – Some VR radiation studies * What we can do at SLAC – NLCTA – FACET July 25, 2008, Crystal experiments at SLAC

Particle-crystal interaction Possible processes: t multiple scattering t channeling t volume capture t de-channeling t volume reflection Volume reflection U Prediction in 1985 -’ 87 by A. M. Taratin and S. A. Vorobiev, First observation 2006 (IHEP - PNPI - CERN) July 25, 2008, Crystal experiments at SLAC d

Angular profile (µrad) Angular beam profile as a function of the crystal orientation The angular profile is the change of beam direction induced by the crystal 5 1 The rotation angle is angle of the crystal respect to beam direction 1 The particle density decreases from red to blue 3 1 - “amorphous” orientation 4 2 - channeling 3 - de-channeling 4 - volume capture 2 5 - volume reflection Rotation angle (µrad) July 25, 2008, Crystal experiments at SLAC

counts Angular profile (µrad) Angular profile µrad Amorphous Rotation angle (µrad) July 25, 2008, Crystal experiments at SLAC

Angular profile µrad Channeling Rotation angle (µrad) July 25, 2008, Crystal experiments at SLAC Angular profile (µrad) counts

counts Angular profile (µrad) Angular profile µrad Volume Reflection Rotation angle (µrad) July 25, 2008, Crystal experiments at SLAC

Volume reflection radiation Relative transversal velocities of positrons (a) and electrons (b) at volume reflection in bent silicon crystal. E = 200 Ge. V, crystal thickness 0. 06 cm, radius of bending 10 m. Yu. Chesnokov et al, IHEP 2007 -16 July 25, 2008, Crystal experiments at SLAC

Volume reflection radiation of 200 Ge. V e+ or e- on 0. 6 mm Si crystal (Rbend=10 m) Yu. Chesnokov et al, IHEP 2007 -16 e+ eamorphous Scaling Eg with E: ~E 3/2 for E<<10 Ge. V and E 2 for E>>10 Ge. V (Gennady Stupakov) July 25, 2008, Crystal experiments at SLAC

Strip crystals Built at IHEP - Protvino and at INFN - Ferrara The main curvature due to external forces induces the anticlastic curvature seen by the beam Crystal size: 0. 9 x 70 x 3 mm 3 Main radius of curvature Radius of anticlastic curvature July 25, 2008, Crystal experiments at SLAC

Quasimosaic crystals Built at PNPI - Gatchina Beam direction Quasi-Mosaic effect (Sumbaev , 1957) n The crystal is cut parallel to the planes (111). n An external force induce the main curvature. n The anticlastic effect produces a secondary curvature n The anisotropy of the elastic tensor induces a curvature of the crystal planes parallel to the small face. Crystal size: 0. 7 x 30 mm 3 July 25, 2008, Crystal experiments at SLAC

O-shaped crystal July 25, 2008, Crystal experiments at SLAC

2007 run breaking news 5 heads multicrystal (PNPI) p July 25, 2008, Crystal experiments at SLAC

RD 22: extraction of 120 Ge. V protons (SPS: 1990 -95) The RD 22 Collaboration, CERN DRDC 94 -11 Large channeling efficiency measured for the first time t Consistent with simulation expectation extended to high energy beams t Experimental proof of multi-turn effect (channeling after multi-traversals) t t Definition of a reliable procedure to measure the channeling efficiency July 25, 2008, Crystal experiments at SLAC

E 853: extraction of 900 Ge. V protons (Tevatron: 1993 -98) At crystal t t Lambertson, crystal t t Extracted significant beams from the Tevatron parasitic, kicked and RF stimulated First ever luminosity-driven extraction Highest energy channeling ever Useful collimation studies Extensive information on time-dependent behavior Very robust July 25, 2008, Crystal experiments at SLAC

The H 8 RD 22 apparatus Goniometer with crystal holders S 3 S 1 vacuum p B 5 B 6 vacuum S 2 H S 4 Si microstrips (AMS) S 5 GC S 6 Si microstrips (AGILE) 70 m t The scintillators S 1 -S 6 produce the trigger t The Si microstrips (AMS & AGILE) give the particle tracks t The gas chamber (GS) and the hodoscope (H) provide a fast beam profile t The goniometer orients the crystal respect to the incoming beam direction July 25, 2008, Crystal experiments at SLAC

Goniometer Assembled at INFN - Legnaro t Two motors for translations n n n 2 μm repeatability 102 mm range (upper stage) 52 mm range (lower stage) t One motor for rotations 360° range n 1. 5 μrad precision n 1 μrad repeatability n July 25, 2008, Crystal experiments at SLAC

The Roman Pot technique 1. The Roman Pot, an historically successful technique for near beam physics: ISR, SPS, TEVATRON, RICH, DESY 2. A CERN in-house technology: ISR, SPS-UA 4, CDF Scattered particles IP X CERN SPS (UA 4) CERN for CDF July 25, 2008, Crystal experiments at SLAC

Roman Pot July 25, 2008, Crystal experiments at SLAC

Technical Status (2) First Roman Pot Detector Package Assembled Roman Pot Motherboard connecting the detector packages in the vacuum to the outside world To be installed in the tunnel by end of April. 3 – 5 more assemblies to be mounted before LHC start-up. Vacuum flange Feed-through Roman Pot Motherboard completed and currently under test. July 25, 2008, Crystal experiments at SLAC Connectors to detector hybrids

Layout of the CRYSTAL experiment July 25, 2008, Crystal experiments at SLAC

Roman Pot tests in the SPS with coasting beam H 8, fix target area (Crystal experiment 2007, RD 22, et. ) • One Prototype of the Roman Pots has been installed and operated in the SPS during the 2004 runs, • Installation in the sextant 5, sector 530 • Counting Room on surface in the blg. BB 5 • Test Roman Pot mechanics, controls and cooling in a realistic beam environment Counting Room Access Point Roman Pot Location • Study RF influence of the beam bunch structure on the silicon detectors and their electronics • Study trigger capability of the silicon detectors with the VFAT trigger chip. July 25, 2008, Crystal experiments at SLAC

SLAC variant for the Crystal experiment Two vertical + two horizontal pots Same design for the vacuum chamber Mall modifications for the mechanical stands All vacuum chambers should be produced by the same company which made all the LHC Roman pots fabrication tooling for free, specific experience on the product: 4 years from R&D, prototyping and mass production Supports and stands can be manufactured in any reasonable good workshop : CERN, INFN, SLAC July 25, 2008, Crystal experiments at SLAC

NLCTA & possible locations of tests 60 Me. V 360 Me. V 2 -6 Me. V July 25, 2008, Crystal experiments at SLAC

2 -6 Me. V Photo-injector Gun and Spectrometer July 25, 2008, Crystal experiments at SLAC

July 25, 2008, Crystal experiments at SLAC

NLCTA tests * What is done – – Studies of mostly p and e+ e- are known to be difficult for channeling VR studies VR radiation just started (paper to be published soon based on 2007 CERN tests) * VR radiation seems best fit for us to start studies from – due to its applicability for e+ or e- collimation of linear collider – due to its potential use for photon source – due to simpler experimental setup on a short base in NLCTA * Will need – Crystal and goniometer (loan, build? ) – gamma detector July 25, 2008, Crystal experiments at SLAC

NLCTA VR radiation tests * Expected energy of gammas (scaled as E 3/2 from theoretical plot on the right): * E=6 Me. V => Eg ~ 4. 5 k. V * E=60 Me. V => Eg ~ 140 k. V * E=360 Me. V => Eg ~ 2 MV Yu. Chesnokov et al, IHEP 2007 -16 Differential radiation energy losses 10 -Ge. V positrons (1) in 0. 045 cm silicon single crystal. The curve 2 is amorphous contribution. July 25, 2008, Crystal experiments at SLAC