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WITCH: studies made in 2005. S. Coeck M. Herbane , V.Yu. Kozlov, I.S. Kraev, N. Severijns, F. Wauters M. Beck, P. Delahaye, A. Herlert, F. Wenander The ISOLDE, NIPNET and TRAPSPEC collaborations In collaboration with: LPC-Caen and University Mainz (K. Blaum). W eak I nteraction T rap for
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WITCH:studies made in 2005 S. Coeck M. Herbane, V.Yu. Kozlov, I.S. Kraev, N. Severijns, F. Wauters M. Beck, P. Delahaye, A. Herlert, F. Wenander The ISOLDE, NIPNET and TRAPSPEC collaborations In collaboration with: LPC-Caen and University Mainz (K. Blaum) WITCH: studies made in 2005 06/02/06 Sam Coeck
Weak Interaction Trap for CHarged particles • Overview • Motivation and overview of WITCH • Where we left off in 2004 • Pulsed Drift Tube • MCP detectors • Conclusion and outlook WITCH: studies made in 2005 06/02/06 Sam Coeck
a=1 Recoil spectrum a=1/3 a=0 a=-1/3 a=-1 Motivation for WITCH Fermi b-decay: H = HV(CV, C’V) + HS(CS, C’S) Standard model: V=1, S=0 (a=1) ; experimentally: S<8% S>0 -> a<1 (a = b-n angular correlation coefficient) WITCH: studies made in 2005 06/02/06 Sam Coeck
~7m Overview of the setup WITCH: studies made in 2005 06/02/06 Sam Coeck
Going for radioactive ions Slide from 15 nov 2004 Monday 8/11/2004 (evening) – Thursday 11/11/2004 (morning): First run of WITCH with radioactive 35Ar • Problem: • Problem with ISOLDE target (CaO) Result: factor of 40 (in the beginning 400) less 35Ar and a lot of 35Cl • The efficiency of the injection into the traps is not high enough yet to handle this WITCH: studies made in 2005 06/02/06 Sam Coeck
Efficiency overview (*) might be underestimated by factor ~5 (**) can be increased to ~80% by using b- decay WITCH: studies made in 2005 06/02/06 Sam Coeck
70cm Pulsed Drift Tube (PDT) WITCH: studies made in 2005 06/02/06 Sam Coeck
Understanding the PDT WITCH: studies made in 2005 06/02/06 Sam Coeck
Understanding the PDT WITCH: studies made in 2005 06/02/06 Sam Coeck
MCP saturation problems • Misinterpretation of: • total intensity • relative intensity • time structure • tuning • Solution: • limit incoming intensity • directly or using attenuating grid • limit operating voltage • to avoid this saturation WITCH: studies made in 2005 06/02/06 Sam Coeck
Position sensitive diagnostics • Slow • Inaccurate position information • Can be difficult to quantify • Fast (1 wire / pulse for now) • 1 full scan / pulse possible • Higher spatial resolution • Still gives timing information • Simple WITCH: studies made in 2005 06/02/06 Sam Coeck
Conclusion • Behavior of PDT is now better understood • MCP saturation effects have been studied and can be avoided • New diagnostics system has been implemented • Various ideas concerning improving the efficiency are ready to be tested • Construction of own ion source has been started, this to gain independance • Tests with new position sensitive recoil ion detector (LPC-Caen) are ongoing • Extensive simulation work has been done on various aspects of the set-up WITCH: studies made in 2005 06/02/06 Sam Coeck
Outlook for 2006 • Further testing of the PDT and injection in the magnetic field (coming weeks) • Further optimize beam diagnostics • Testing + installation of WITCH 60keV 39K ion source • Testing of the isobaric purifying power of the cooler trap • Optimizing buffergas circuit for Penning traps • Installation of the new position sensitive recoil ion detector • Test possible background from b-particles on recoil ion detector • First ‘proof of principle’ experiment Thank you for your attention WITCH: studies made in 2005 06/02/06 Sam Coeck