1 Beamline DayTimePresenterTopic Thurs9:00C.BoothMICE Target Wed16:00K.TilleyRecent Beamline Design Work Wed16:30T.RobertsMICE Beamline Performance + Emittance Analysis MICE Collaboration Meeting, RAL, Oct2004

Status of Target Design Chris Booth Sheffield 28 th October 2004

Diaphragm spring Target Array of coilsMagnet(s) Position measurement Schematic design Linear Drive

Draft Specification Transit: 40 mm Entry ≥ 5 mm into beam in ≤ 2 ms (see plot) Cycle time: 20 ms Positioning accuracy:  0.5 mm Timing accuracy: ~ 0.2 ms Frequency: (baseline) 1 to 3 Hz on demand (optimal) 1 to 50 Hz Maximum proton rate: 1.4  per second Must operate in vacuum and radiation environment Must not interfere with ISIS operation!!

Target edge trajectory

Diaphragm Spring suspension Frictionless “bearing” allowing vertical movement Must keep armature on axis to  0.2 mm (for magnet and position monitor) Design of small spring obtained from Tom Bradshaw (RAL) Scaled up to allow ≥40 mm travel Finite element studies to check stress and lifetime issues (Lara Howlett) Be-Cu sheet procured Wire-erosion performed in Eng. Dept. workshop

Linear Drive (1) Tests with first prototype –Moving magnet shuttle (2 magnets) –Static single/double coil excitation –No commutator ~ radial field SN N S (Armature)

…however! Current armature/coil design does not give required acceleration –280 N kg –1 at 20 A mm –2 –Need ~950 N kg –1  revised armature design  current density 35 A mm –2 for short pulses. Thus effective cooling essential (proposing placing coils in conductive resin, surrounded by water cooling jacket…)

Improved armature design Sectored magnets – fixed together with aircraft glue Also, other materials eg. SmCo?

“3-phase” drive Magnetic actuator plus Hall switches  bipolar drive

Radiation concerns Studying documented radiation hardnesses of target systems/components expected to be dominated by beam loss produced during target insertion hope to make measurements at ISIS in spring

Plans for next months Complete revised design - Optimised coil, armature design - 3-phase switched drive circuit Currently mounting 1st prototype vertically on diaphragm springs - Measure lateral stability - Debug position readout system, check read speed - Develop cooling and temperature measurement system - Switch to new drive as soon as available Develop control hardware & software

paul drumm, mutac jan Recent Beamline Design Work Kevin Tilley, ISIS, RAL Recent beamline revisions Description of SEPT04 beamline design Aims Calculation of beam momentas Envelopes and assessment with Turtle Future Plans 1

paul drumm, mutac jan Recent Design Revisions JAN04 → first, new design concept (JAN04A → lower emittance, higher Good Mu rate example) MAR04 → Realistic geometry/constraints, C2H4 Mu purity JUNE04 → Modified for correct definition (JUNE04A → proposed chgs to lower TOF0, incr Good Mu) … to Current work - 2

paul drumm, mutac jan Motivations for new design - SEPT04 To reduce muon design momentum from 236 → 206MeV/c Maintain (usual cut) whilst at the same time, set the design for:- Low TOF0 singles rate High Good-muon rate. 3

paul drumm, mutac jan Muon Momenta's Defining the beamline momentums For at 206MeV/c at exit of Pb, working backwards through the Pb and the C2H4 gives a value of 233MeV/c needed after the decay solenoid. [NB energy loss due to PIDs etc not included] 4 Pion Momentum For both a lower TOF0 singles rate, and for a high intensity final muon beam, we can use the high intensity working point relation from similar beamlines (PSI uE1/uE4 & RAL-RIKEN): -> 390MeV/c Graph taken from PSI,SIN Users Handbook

paul drumm, mutac jan Results of Optics work (Pi+Decay Sectn) 7 Now 3.7Tesla Full width beam profile Shows

paul drumm, mutac jan Results of Optics work (Muon Extraction) RMS beam profile Shows Showing 8

paul drumm, mutac jan Assessment with TTL Looking at usual momentum width, +/-1% ~ 206MeV/c: (i) Beam & emittance > Pb. xx' larger distribution (improvable with quad optics) yy' 5.9pi & well matched ~206MeV/c NB. Overall beam distribution: still has previous aberrations. 9 (ii) Indications of effect on TOF0 rates Total particles (from 10^6 initial pions) at proposed TOF0 position [JUNE ] -> [SEPT ] (iii) Indication of Good muon intensities? Total muons in desired matched yy' distribution (usual cuts, & from 10&7 initial pions): [JUNE ] -> [SEPT ] ? as desired indicative as desired

paul drumm, mutac jan Future design tasks PID/Beamline materials revision Switch to Q4-Q9 DFD FDF for better balancing (usual cut) Find reason for (& solve?) current aberrations in wider beam distribution ie:- making =p-design attend to xx', yy' aberrations (improving match for wider dp/p) Produce various (p, ) cases as required for MICE Beam steering correction schemes (using trim coils on Quads etc.) And as always… Continue TTL (/other) v g4beamline comparisons (and then improving realism of the design/evaluation codes) 14

MICE Beamline Performance & Emittance Analysis Tom Roberts Muons, Inc. October 27, 2004

Summary of this Simulation The SEPT04 magnet currents/positions (optics) but also: –First guess of the beamline vacuum, windows, air gaps. Also inclusion of PID materials in beamline. More detailed implementation of Tracker1 and Tracker2 –Vacuum with windows –5 planes, 1.5 mm scintillator each, located as in the TRD TRD configurations for everything except a few minor things (absorber and RF window shapes, RF Cavity size, Cherenkov2 modeled as a circle)

The additional effect of the vacuum windows, air gaps & PID materials in this simulation. μ + central momentum in Tracker1 – design206 MeV/c μ + central momentum in Tracker1 – achieved183 MeV/c This highlights the potential for further differences, between the design goals and the results of this current simulation.

Summary of Rates DescriptionLAHETMARSGeant4 TOF TOF Tracker Tracker TOF Good μ Values are events per millisecond of Good Target and good RF. Good μ + = TargetDet & TOF0 & TOF1 & Tracker1 & Tracker2 & TOF2 & TOF1(μ + ) & TOF2(μ + )

Emittance Computation - method SEPT04 beamline optics + PIDs, air & vacuum windows Absorbers are empty, no RF Analysis chain: g4beamline → for009sum → ecalc9f → excel for009sum combines multiple FOR009.DAT files, and imposes cuts: –Require through tracks (hits in all 10 Tracker stations) –Ptot cut, applied in the first region (Tracker1a) All cuts in ecalc9f are disabled (except PID), so the only cuts are: –Require each track to be a μ + in all 10 Tracker stations –Require through tracks (hits in all 10 Tracker stations) –Ptot cut in Tracker1a (+/-5MeV/c ~ momentum of interest) A shell script was used to automate the interface to ecalc9f and connect the analysis chain together

Emittance Computation 205MeV/c ≈ 8.2 pi mm rad

Conclusions The SEPT04 beamline optics were assessed, adding also the PIDs, air & vacuum windows in this simulation. TOF0 rates are lower than JUNE04 at ~ 2.5MHz The Good muon count is comparable to JUNE04. In this analysis, the input emittance for the bin +/-5MeV/c about 205MeV/c is ~ 8.2 pi mm rad. The transverse emittance computed here increases in the empty cooling channel, at all momentums considered. A further beamline optics which accounts fully for the PID, air & vacuum windows should be produced and re-evaluated.