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June 2006 Paul Mumby-Croft University of York 1Page
TACTIC: A New Detector for Nuclear Astrophysics
An update for the ACTAR meeting, Daresbury, UK 12-13th June 2006.
Paul Mumby-Croft
Nuclear Physics Group, University of York, UK
June 2006 Paul Mumby-Croft University of York 2Page
TRIUMF Annular Chamber for the Tracking and
Identification of Charged Particles
Original concept: L. Buchmann, TRIUMF
June 2006 Paul Mumby-Croft University of York 3Page
How is it going to work?
● 90% helium 10% CO2 gas mixture● Pressure of a few hundred mbar● Drift voltage ~100V/cm
June 2006 Paul Mumby-Croft University of York 4Page
Technical drawings
(Daresbury, P. Amaudruz)
June 2006 Paul Mumby-Croft University of York 5Page
Technical drawings
(Daresbury, P. Amaudruz)
June 2006 Paul Mumby-Croft University of York 6Page
Technical drawings + GEANT4
(G. Ruprecht, TRIUMF)
June 2006 Paul Mumby-Croft University of York 7Page
Technical drawings + GEANT4
(G. Ruprecht, TRIUMF)
June 2006 Paul Mumby-Croft University of York 8Page
The cathode cage● Purpose: to reduce background ionisation
electrons
June 2006 Paul Mumby-Croft University of York 9Page
The End.
Thanks to the TACTIC collaboration: A. Laird1, G. Ruprecht2, D. Gigliotti2, P. Amaudruz2, L. Buchmann2, S. Fox1, B.
Fulton1, T. Kirchner2,R. Openshaw2, M. Pavan2, J. Pearson2, G. Sheffer2, P. Walden2.
Thanks to R. Veenhof3 for help with GARFIELDThanks to Rob, Kal, and Roy at Daresbury
1) Department of Physics, University of York, York, YO10 5DD, UK.2) TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
3) CERN, CH-1211 Genève 23, Switzerland
June 2006 Paul Mumby-Croft University of York 10Page
Technical drawings
(Daresbury, P. Amaudruz)
June 2006 Paul Mumby-Croft University of York 11Page
Motivation
● To investigate astrophysical charged-particle reactions● Low energies and low flux RIBs● Need good solid angle coverage (c.f. the LEDA array)● Initial design caters for 8Li(a, n)11B reaction● Recent r-process models are sensitive to this reaction rate (Sasaqui et al. ApJ 634 2005)● Transitions to excited states make important contribution● Factor of ~2 difference in published reaction rates (Boyd
et al. 1992; Gu et al. 1995; Mizoi et al. 2000; Paradellis et al. 1990).
June 2006 Paul Mumby-Croft University of York 12Page
The Gas Electron Multiplier
● Thin Kapton foil (50um) with 10um copper on each side● Etched with 50um diameter holes
(Pictures from CERN)
June 2006 Paul Mumby-Croft University of York 13Page
The cathode cage
June 2006 Paul Mumby-Croft University of York 14Page
E-potential around the cathode cage
● Electrons want to drift ‘uphill’
June 2006 Paul Mumby-Croft University of York 15Page
Summary
● New detector for charged particle reactions● Active target configuration using GEMs● Measures timing and total energy, allowing vertex reconstruction● Technical drawings very near completion, construction begins at York this summer.
June 2006 Paul Mumby-Croft University of York 16Page
June 2006 Paul Mumby-Croft University of York 17Page
June 2006 Paul Mumby-Croft University of York 18Page
What do we see?
June 2006 Paul Mumby-Croft University of York 19Page
Ionisation in TACTIC
June 2006 Paul Mumby-Croft University of York 20Page
Variation of Gain with Voltage and Pressure.
June 2006 Paul Mumby-Croft University of York 21Page
What has been done so far?
(G. Ruprecht, TRIUMF)
June 2006 Paul Mumby-Croft University of York 22Page
June 2006 Paul Mumby-Croft University of York 23Page
June 2006 Paul Mumby-Croft University of York 24Page
June 2006 Paul Mumby-Croft University of York 25Page
June 2006 Paul Mumby-Croft University of York 26Page
Resolution
June 2006 Paul Mumby-Croft University of York 27Page
June 2006 Paul Mumby-Croft University of York 28Page
E-potential around the cathode cage
June 2006 Paul Mumby-Croft University of York 29Page
Electric field strength around the wires.
June 2006 Paul Mumby-Croft University of York 30Page
Drift time: is it uniform in phi?
Drift velocity and drift time are fairly insensitive to E (V/cm) at these energies.
June 2006 Paul Mumby-Croft University of York 31Page
Overview of presentation
● What is a TACTIC?● Why do we need it?● How is it going to work?
