Status of the External Solenoidal Spectrometer for the TSR Robert Page Why an external spectrometer? Solenoidal spectrometer Baseline design parameters Current status

External Spectrometer for the TSR

Why an External Spectrometer? “The superior properties of the cooled extracted beam from the TSR compared to the direct beam from HIE-ISOLDE... will be of benefit to many classes of external spectrometers that can exploit these qualities.”

Why an External Spectrometer?

What external spectrometer options? Active target T-REX + Miniball GASPARD Solenoidal spectrometer

Solenoidal spectrometer concept CM Energy: CM Angle: z θ cm θ lab v lab v0v0 V cm

HELIOS at Argonne J.C. Lighthall et al.,NIM A622 (2010) Si PSDs 12 mm × 56 mm × 0.7 mm 9 mm × 50.5 mm active area square 23 mm × 710 mm 340 mm active length

“ISOL-SRS” grant awarded!

“ISOL-SRS” grant STFC funding for Detector array for internal spectrometer External solenoidal spectrometer Total project costs awarded, including manpower, is £4.8M £3.2M “new money” mostly for materials Not funded: Gas-jet target for internal spectrometer Universities of Aarhus and Lund seeking funding Solenoidal magnet

Baseline Design Hexagonal hollow array of DSSDs Overall Si length  0.5 m (easily upgraded with extra modules) Compact design to minimise distance from interaction point to axis 1 mm thick silicon stops 12 MeV protons 17 MeV deuterons 20 MeV tritons… 1mm pitch in z 1mm pitch in x – allows better axis crossing point z estimate Overall active area >80% Cooled to -20 ℃ ASIC readout

Acceptance Simulations GEANT4 simulations by M. Labiche

EXTERNAL SPECTROMETER: d( 24 Ne,p) MeV/u HIE-ISOLDE beam: 38 keVCooled TSR beam: 22 keV Q-value resolution Calculations by P.A. Butler

Solenoidal Spectrometer for the TSR Install at CERN 1 st quarter of 2019 LS (if delayed 1 year) Exploit with HIE beams Exploit with TSR beams from 2023

Current Status UK STFC grant started 2015 Realistic layouts for ASICs, etc. Defining final parameters for Si DSSDs ASIC delivery now due for R 3 B

4T, ActiveShield technology MRI magnet available (type OR66) Large bore of up to 90 cm diameter, ~2m long Magnet comes with power supply, cold-head and compressor, and other equipment and should be operational Installation requires cool-down (6500 litres of LHe, ramping and shimming (passive and active shimming) Specifications: MRI magnet: Oxford OR66 Brisbane = HeliOz magnet?!

Magnet funding opportunity!

Conclusions Thanks to: Peter Butler, Sean Freeman, Marc Labiche, Ian Lazarus, Alan Grant, Mike Cordwell, Dave Seddon, Jim Thornhill, Dave Wells, John Simpson, Dave Jenkins, … Funding awarded for external spectrometer Preliminary design work is underway Efforts to obtain ex-MRI magnet continuing

Why a solenoidal spectrometer? CM Energy:CM Angle: z θ cm θ lab v lab v0v0 V cm

OR66 magnet fringe field Space allocation for magnet assumed to be 10 x 10m

Energy Resolution 22 – 55 keV FWHM (protons) J.C. Lighthall et al.,NIM A622 (2010) 97

Position Resolution J.C. Lighthall et al.,NIM A622 (2010) 97 5 MeV p + 12 C 0.5 mm FWHM 2 MeV p + 12 C 1.2 mm FWHM slit width 0.5 mm

General Considerations Detectors close to axis – t.o.f.  cyclotron period Central hole for beam Best possible energy resolution Highest possible efficiency Good position resolution Good timing resolution Flexibility – different configurations Operation within magnetic field Cooling of detectors …

Operation in magnetic fields? T.J. Barber et al., NIM A538 (2005) 442 “Dangerous mechanical resonances exist which can lead to the breaking of bond wires if time varying currents are passed through them in a magnetic field.”

Si operation in magnetic fields? B = 1 T