One way to improve first class mass measurements @ ISOLTRAP Poilvert Nicolas, student session 2005

How do we measure masses? THE basic idea: B + Use a B field → radial confinement Cyclotron frequency ωc= qB/m q,m Problem: motion not axially bound 2) super impose an E field → axial confinement Poilvert Nicolas, student session 2005

The motion of the ion(s) Three independent harmonic eigenmotions 1. Axial motion: 2. Magnetron motion (slow): 3. Reduced Cyclotron motion (fast): Reduced Cyclotron A=100 amu, q=1, B=6 T f+  1 MHz f-  1 kHz fz  44 kHz Poilvert Nicolas, student session 2005

Beam coming from Isolde Poilvert Nicolas, student session 2005

The experimental apparatus Precision Penning Trap MCP / Channeltron Detector Penning Trap : measure Cyclotron frequency determination Penning Trap : cooling Isobaric cleaning 2.7 keV ions ISOLDE 60 keV ions Paul Trap : RFQ-Buncher Beam preparation Poilvert Nicolas, student session 2005

But how exactly do you measure the mass? Quadrupole exitation at ωrf : exact conversion between cyclotron motion and magnetron motion at resonance G.Bollen et al. resonant at ωrf = ωc Courtesy of C. Yazidjian Poilvert Nicolas, student session 2005

But how exactly do you measure the mass? MCP / Channeltron TOF Precision Penning trap B=5.9T Poilvert Nicolas, student session 2005

How to determine B precisely? a very high precision on m depends directly on a high precision of the B field magnitude The solution is to measure B precisely using reference masses (alkali, carbon clusters,…) Overall accuracy: Poilvert Nicolas, student session 2005

The carbon cluster solution Why Carbon clusters? Pulsed YAG laser λ = 532 nm C13+ Gives us mass references throughout the nuclear chart C5+ (12C)60 with 12C isotope C22+ Poilvert Nicolas, student session 2005

Nuclear chart C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 More reference mass Reference mass

Precision Penning trap Carbon cluster ion source My job MCP / Channeltron TOF detector Find the right potentials in order to guide and inject the carbon cluster ions into the preparation trap Precision Penning trap RFQ cooler buncher 2.7 keV ion bunches ISOLDE beam 60 keV Carbon cluster ion source Laser Poilvert Nicolas, student session 2005

Thanks for your attention! Not to forget: the ISOLDE group and the ISOLTRAP collaboration Special thanks to my supervisors Poilvert Nicolas, student session 2005