S Stahl Cryogenic Image Charge Detection Cryogenic Image

S. Stahl: Cryogenic Image Charge Detection Cryogenic Image Charge Detectors S. Stahl, CEO Stahl-Electronics

S. Stahl: Cryogenic Image Charge Detection Outline I. Motivation II. Ion Motion in Traps II. How does Image Charge Detection work III. Resonant Detection IV. Resistive Cooling V. Single Pass detection and Outlook

S. Stahl: Cryogenic Image Charge Detection I. Motivation: Why using cryogenic charge detectors? l Detect few or single particles (Antiprotons) without loosing them l Count their number and measure their energy (sub-e. V) in a non-destructive way l Cool them (resistive cooling) to milli-e. V or lower (applies for traps) l Useful to place detectors inside your cryogenic setup

S. Stahl: Cryogenic Image Charge Detection Penning Trap Motion Charged Particle Mass m, Charge q Þ Lorentz-force: radial confinement free cyclotron motion: Þ Electrostatic potential: axial confinement Þ leads to axial oscillation

S. Stahl: Cryogenic Image Charge Detection Resulting ion motion 3 degrees of freedom: Axial Motion ~1 MHz Energy: 0. . . e. V. . . ke. V Reduced Cyclotron Motion ~10 MHz Magnetron Drift ~10 k. Hz

S. Stahl: Cryogenic Image Charge Detection Penning Trap: Some Real-world designs Precision trap for single-ion mass analysis (GSI / Univ. Mainz, Triga) Precision trap for single-ion g-factor determinations (Univ. Mainz) „Shiptrap“ for mass analysis of short-lived isotopes (GSI)

S. Stahl: Cryogenic Image Charge Detection II. How does image charge detection work ? Ions, Electrons, Protons, . . are electrically charged particles Every Moving Charge = Electrical Current n a c u o y > = ! t i e r u s a e m

S. Stahl: Cryogenic Image Charge Detection Implementation Ion Motion: Z

S. Stahl: Cryogenic Image Charge Detection Implementation Axial Motion: induced image currents Z amount of current: Ipk = Dzion/ D · w · q (Schottky et al. . ) still very small: 0. 1 p. Aeff

S. Stahl: Cryogenic Image Charge Detection Signal Strength: Ohm‘s Law: U = Z · Ieff => make Z as big as possible ! But how? ZC = 1/(w. C) Leave away R, use existing parasitic capacitance C ! Few pico. Farad Ohm‘s Law: U = Z · Ieff = Ieff/(w. C) typical values: 1 n. Vrms, singly charged particle in 5 p. F-Trap, 1 e. V small !

S. Stahl: Cryogenic Image Charge Detection Image Charge of Cyclotron Motion x y „FT-ICR“ fourier-transform-ion cyclotron resonance Remember: Important Parameters -parasitic capacitance of your pickup electrodes (e. g. 1 p. F excellent. . . 200 p. F poor) -Low noise / high gain of amplifier (voltage noise ideally < 1 n. V/rt Hz) => See Ilia‘s talk

S. Stahl: Cryogenic Image Charge Detection Origin of Parasitic Capacitances Cpar Trap (pickup plates) Cables (Leads) 2. . . 15 p. F ~ 125 p. F Input Cap. Amplifier 5. . . 15 p. F => put amplifier close to the trap

S. Stahl: Cryogenic Image Charge Detection Miniaturization helps improving parasitic capacitances Ilia‘s work in progress: Tip of a ball-pen Scaling rule: Cparasitic~ Size Tracks ~ 1 p. F

S. Stahl: Cryogenic Image Charge Detection III. Sensitivity Improvement: Resonant instead of broadband detection I measured signal: U=Z·I ZLC = QLC · |ZC, parasitic| wion = w. LC = 1/√(LC) resonant broadband (given : rion, D) enhancement factor ~100 (T=300 K) ~2000 (T = 4 K) Þcryogenic components this idea applies for axial detection as well as for FT-ICR !

S. Stahl: Cryogenic Image Charge Detection Examples of high-Q-coils: 500 k. Hz-coil 30 MHz-coil for FT-ICR detection of heavy masses for FT-ICR of hydrogenlike ions (g-factor, Mainz) gold plated copper (Shiptrap / MATS) Nb. Ti wire on Teflon

S. Stahl: Cryogenic Image Charge Detection Applications and Examples of non-destructive electronic detection schemes g-factor measurements: neccessity to know the magnetic field strength B FT-ICR-signal (resonant): FWHM of 6· 10 -10, measurement time: 120 sec (=Fourier-Limit) Ekin ~ 1 e. V wc = q. B = w + + wm 12 C 5+

S. Stahl: Cryogenic Image Charge Detection Counting single ions. . . how many ions are inside the trap? => just count them!

S. Stahl: Cryogenic Image Charge Detection IV. Resistive Cooling induced current creates thermal energy in R => dissipative effect, => exponential decay of amplitude t= R= m · D² q² · R Q w·C ion 12 C 5+ D 5. 5 mm Protons, ‘‘’ 131 Xe 44+, 20 mm e-, e+, 0. 7 mm t 23 ms 49 ms 44 ms 10. 9µs for Q = 2000, f = 0. 4 MHz, C = 20 p. F (except e-, e+)

S. Stahl: Cryogenic Image Charge Detection of cold particles: Þpossibility to detect cold ions

S. Stahl: Cryogenic Image Charge Detection Interaction between ion(s) and detection Circuit: Noise on LC-Circuit Ph. D Thesis S. Stahl, 1998

S. Stahl: Cryogenic Image Charge Detection Bolometric-electronic Detection of cold ions

S. Stahl: Cryogenic Image Charge Detection V. Single Pass detection and Outlook Detecting ions passing through an electrode Flying by only once: challenging: short interaction time Dt => wide frequency spread => a lot of noise Fourier-Limit: Df = 1/Dt typ. Interaction time: 1µs (Ar, 5 ke. V, 10 cm)

S. Stahl: Cryogenic Image Charge Detection Figure-of-Merit Single-Pass Charge Detector Competition: Ion Charge Amplifier Noise Charge l l l Low Voltage Noise Low Current Noise => ENC (equivalent Noise Charge) Silicon (best-of-class) typ. 100 e Ga. As 10 to 20 e Improved design Ga. As 2 to 5 e (beyond-AVA) very low voltage/current noise + extremely small input capacitance

S. Stahl: Cryogenic Image Charge Detection Single ion Detection (single-pass) l l Single Ion Lithography Future (? ) single Antiproton fly-through detection IOM Leipzig / Univ. Leipzig implant single atoms in substrates NV-centers (Quantum Computing, novel sensors)

S. Stahl: Cryogenic Image Charge Detection Examples of Cryogenic Preamplifiers: 4. 2 K to 100 m. K Gallium-Arsenide-based - ultra low noise image charge amplifiers - with single particle charge sensitivity Customized FET chips Nex. Gen 3 Very low 1/f noise Customized Readout Amplifiers State-of-the-Art Sensitivity (<< 1 n. V/rt Hz, qrms < 5 e) -image charge detection -general readout of information in cold regime

S. Stahl: Cryogenic Image Charge Detection g-factor setup Mainz: vertical 4 Kdewar setup (g-factor, Mainz) 4 K-electronics section 4 K-axial amplifier g-factor trap 4 K-broadband FT-ICR amplifier ( Mainz 2004 )

S. Stahl: Cryogenic Image Charge Detection Penning Trap Variants - classical hyperpolical electrodes B-field - cubic type trap (chemistry) - 3 pole-Brown-Gabrielse-type trap Laser, Microwaves, Ions, . . . A. Marshall et al. Rev. Mass. Spec. 17, 1 (1998). L. S. Brown, G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986).