12/12/04 1 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF UK plans for Energy spectrometer studies University College London Stewart Boogert Alexei Liapine Stephen Malton David Miller Matthew Wing Cambridge University Mark Slater Mark Thompson David Ward New UK groups joining effort in design and prototyping of energy spectrometer for a International Linear Collider Started with determination of the top quark mass from threshold scans Luminosity spectrum and it's determination from Bhabha events Energy spectrometer and associated Cavity BPMs Difficult to give a talk when you are new to the field!

12/12/04 2 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Introduction ● Simulation work – Luminosity spectrum – Top threshold – Energy biases ● Design – Straw man design of energy spectrometer ● End station A – New test beam project at SLAC ● ATF project – Gain experience in Cavity BPMs – Readout and analysis of data

12/12/04 3 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Top quark simulation ● Aim : measure top quark mass to few parts in 10 4 ● Top quark measurement require four things – beam energy measurements to better than 10 4 – luminosity spectrum determination – measurement of the energy spread – Knowledge of the beam collision process

12/12/04 4 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Luminosity spectrum ● Centre of mass energy at an ILC not unique value due to – Initial state radiation – Beamstrahlung – Linac energy spread ● Energy spectrometer will only measure the average pre-collision beam energy – Possible to measure the disrupted beam energy downstream – Must understand the differences between spectrometer measurements and collision energy

12/12/04 5 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Up/down stream energy bias ● Full linac and BDS simulations from FONT group (G. White) – 550 bunches tracked though “TESLA” accelerator – Top right bias between collision and pre and post collision centre of mass energy ● Significant bias – few % between IP and up and downstream measurements ● Correlated with bunch collision geometry

12/12/04 6 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Simple “strawman” spectrometer design ● Possible designs – Three magnet bend ● Requires precision knowledge of only 1 dipole ● measure deflection – Four magnet chicane ● measure position shift in beam ● At least two dipoles must be precisely known ● BPMs work in the optimal regime ● Easier to perform calibration BPM triplet Dipole

12/12/04 7 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF End station A test beam ● Collaboration of – Notre Dame/ UC Berkeley/ UC London/ Cambridge / SLAC ● End station beam – Momentum : 28.5 GeV – Particles : single bunch – Bunch per train : 1 or 2 – Bunch spacing : 20 – 400 ns – Rep. rate : 10 Hz ● Loads of diagnostics at ESA – Wire array – 6 BPMs (dispersive,angle,position)

12/12/04 8 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF End station A test beam ● Recycled components from SLAC – Different geometry BPMs compared with NanoBPM ● BPMs – 2856 Mhz, rectangular geometry ● Girder – Spear girder ● ESA/ATF – Must evaluate difference in these facilities for spectrometer tests

12/12/04 9 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Possible UK contributions to T-474 and NanoBPM ● ESA spectrometer test beam – Integration of the other beam line instrumentation – Multi-axis movers for the BPMs ● Off the shelf solution would be expensive ● Cam roller magnet movers, developed by SLAC – Readout and control – Analysis ● Nano BPM ATF – Currently contributed a little to software and DAQ – Move onto ● Analysis (Malton/Slater) ● modeling of the BPMs (Liapine) ● DAQ (Boogert) ● Software, eg mat2root (Slater)

12/12/04 10 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF ATF NanoBPM project ● Well advanced project to learn techniques and skills required to build a spectrometer – State of the art motion control – Mechanical & thermal stability – Read out and control in good shape ● Inclusion of the KEK NanoBPM project the extraction line looks almost like a single magnet spectrometer

12/12/04 11 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Experience at ATF December 2004 ● Stephen Malton – Analysis of Cavity BPM signal – Calculating energy deposited in cavity ● Currently catching up with Orimoto, Walston and Smith ● Mark Slater – Readout of NanoBPM data performed in Matlab. – Analysis in ROOT – conversion of mat files to root files – very useful for collaborative data analysis ● Stewart Boogert – Worked on the readout and data acquisition ● ATF corrector control ● MATLAB readout ● Alexei Liapine – Cavity BPM “expert”, to work on the modeling of cavity BPMs – Just missed this visit to KEK due to UK visa problems

12/12/04 12 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF UK Interests ● Alignment – Oxford working on linac alignment, similar techniques could be applied to a spectrometer. See subsequent talk in the session ● Spectrometer time stability – Takes time (how much is unknown) to aqumulate enough statistics from physics events ● Energy calibration – Scale of threshold scan ● Basic accelerator science – Cavity BPMs and RF electronics – Model of BPMs when beam is in the centre and axial needs a new model, much, much more on this later today

12/12/04 13 Stewart Boogert (UCL) Second Mini-workshop Nano project at ATF Conclusions ● UK are the newcomers to the NanoBPM collaboration – Marc and his teams assistance greatly appreciated – Learning about analysis and daq for cavity nano BPM project – Valuable experience for ESA test beams ● ESA cavity BPM tests – UK involved from the start – Limited beam time (~weeks during 2005) – UK will probably contribute hardware as well as manpower ● Modeling of cavity BPMs ● UK groups finding their feet in Cavity BPM world, thanks to US groups for all the assistance.