Synopsis A new method for cooling beams of any ion is introduced. The method is autoresonance acceleration of ions inside an Electrostatic Ion Beam Trap. Intrabunch collisions of trapped (molecular) ions transfer energy from the “cold” part of the population of the ion distribution to the “hot” part, which, in turn, evaporates from the bunch. As a result, bunches of ions were cooled from about 45 K to well below 1 K.

A new hybrid electrostatic ion beam trap (HEIBT) is designed and simulated for low-energy ion-ion, ion-neutral merged beam collision studies as well as ion-laser interaction experiments. The HEIBT is made possible by the design of dichroic electrostatic mirrors that reflect or transmit ion beams of different charge and energy. The experimental setup allows fragment imaging detection of the investigated reaction products ejected outside the trap.

Isomerization and carbon chemistry in the gas phase are key processes in many scientific studies. Here we report on the isomerization process from linear $${{\rm C}}_{10}^ -$$ to its monocyclic isomer. $${{\rm C}}_{10}^ -$$ ions were trapped in an electrostatic ion beam trap and then excited with a laser pulse of precise energy. The neutral products formed upon photoexcitation were measured as a function of time after the laser pulse. It was found using a statistical model that, although the system is excited above its isomerization barrier energy, the actual isomerization from linear to monocyclic conformation takes place on a very long time scale of up to hundreds of microseconds. This finding may indicate a general phenomenon that can affect the interstellar medium chemistry of large molecule formation as well as other gas phase processes. Isomerization is a basic process in nature, with implications for chemical reactivity including in space. Here, the authors observe ultraslow isomerization in an isolated gas-phase carbon chain to its cyclic isomer lasting up to hundreds of microseconds, which may impact the creation of larger carbons in the interstellar medium.

A novel experiment has been commissioned at the Weizmann Institute of Science for the study of weak interactions via a high-precision measurement of the beta-neutrino angular correlation in the radioactive decay of short-lived(6)He. The facility consists of a 14 MeV d + t neutron generator to produce atomic(6)He, followed by ionization and bunching in an electron beam ion source, and injection into an electrostatic ion beam trap. This ion trap has been designed for efficient detection of the decay products from trapped light ions. The storage time in the trap for different stable ions was found to be in the range of 0.6 to 1.2 s at the chamber pressure of similar to 7 x 10(-10) mbar. We present the initial test results of the facility, and also demonstrate an important upgrade of an existing method (Stora et al., 2012) for production of light radioactive atoms, viz.He-6, for the precision measurement. The production rate of(6)He atoms in the present setup has been estimated to be similar to 1.45 x 10(-4) atoms per neutron, and the system efficiency was found to be 4.0 +/- 0.6%. An improvement to this setup is also presented for the enhanced production and diffusion of radioactive atoms for future use.

Isomerization and carbon chemistry in the gas phase are key processes in many scientific studies. Here we report on the isomerization process from linear C-10(-) to its monocyclic isomer. C-10(-) ions were trapped in an electrostatic ion beam trap and then excited with a laser pulse of precise energy. The neutral products formed upon photoexcitation were measured as a function of time after the laser pulse. It was found using a statistical model that, although the system is excited above its isomerization barrier energy, the actual isomerization from linear to monocyclic conformation takes place on a very long time scale of up to hundreds of microseconds. This finding may indicate a general phenomenon that can affect the interstellar medium chemistry of large molecule formation as well as other gas phase processes.

We present an experimental plan to study the weak interaction by measuring the electron-neutrino angular correlation from radioactive beta-emitter atoms, He-6 being the first case. Radioactive atoms, produced by a neutron-induced reaction, will diffuse to an electron beam ion source that ionizes, bunches and then injects them into an electrostatic ion beam trap where the angular correlation will be measured. We have tested the trap with stable ions and found the storage time to be 0.6 to 1.2 s for different ions. We have also performed the production experiment for He-6 with a production rate of similar to 10(5) atoms/s. We present the current status of this project and future plans.

The bubble-assisted Liquid Hole-Multiplier (LHM) is a recently-introduced detection concept for noble-liquid time projection chambers. In this “local dual-phase” detection element, a gas bubble is supported underneath a perforated electrode (e.g., Thick Gas Electron Multiplier – THGEM, or Gas Electron Multiplier – GEM). Electrons drifting through the holes induce large electroluminescence signals as they pass into the bubble. In this work we report on recent results of THGEM and GEM electrodes coated with cesium iodide and immersed in liquid xenon, allowing – for the first time – the detection of primary VUV scintillation photons in addition to ionization electrons.

Autoresonance (AR) cooling of a bunch of ions oscillating inside an electrostatic ion beam trap is demonstrated for the first time. The relatively wide initial longitudinal velocity distribution is reduced by at least an order of magnitude using AR acceleration and ramping forces. The hot ions escaping the bunch are not lost from the system but continue to oscillate in the trap outside of the bunch and may be further cooled by successive AR processes. Ion-ion collisions inside the bunch close to the turning points in the trap's mirrors contribute to the thermalization of the ions. This cooling method can be applied to any mass and any charge.

A novel experiment has been commissioned at the Weizmann Institute of Science for the study of weak interactions via a high-precision measurement of the beta-neutrino angular correlation in the radioactive decay of short-lived ^6He. The facility consists of a 14 MeV d+t neutron generator to produce atomic ^6He, followed by ionization and bunching in an electron beam ion source, and injection into an electrostatic ion beam trap. This ion trap has been designed for efficient detection of the decay products from trapped light ions. The storage time in the trap for different stable ions was found to be in the range of 0.6 to 1.2 s at the chamber pressure of ∼7×10^-10 mbar. We present the initial test results of the facility, and also demonstrate an important upgrade of an existing method for production of light radioactive atoms, viz. ^6He, for the precision measurement. The production rate of ^6He atoms in the present setup has been estimated to be ∼ 1.45×10^-4 atoms per neutron, and the system efficiency was found to be 4.0±0.6%. An improvement to this setup is also presented for the enhanced production and diffusion of radioactive atoms for future use.

Among the advantages of an electrostatic ion beam trap (EIBT), which is based on purely electrostatic fields, are mass-unlimited trapping and ease of operation. We have developed a new system that couples an electrospray ion source to an EIBT. Between the source and EIBT there is a Paul trap in which the ions are accumulated before being extracted and accelerated. After the ion bunch has entered the EIBT, the ions are trapped by rapidly raising the voltages on the entrance mirror. The oscillations of the bunch are detected by amplifying the charge induced on a pickup ring in the center of the trap, the ion mass being directly proportional to the square of the oscillation period. The trapping of biomolecules in the RF-bunching mode of the EIBT is used for measurement of mass spectra and collision cross sections. Coalescence of bunches of ions of nearby mass in the self-bunching mode is also demonstrated.

A Velocity Map Imaging (VMI) spectrometer has been designed and integrated with an electrostatic ion beam trap to study delayed electron emission from trapped polyatomic anions upon photodetachment. The VMI spectrometer is small in size and can record a wide range of photoelectron energies, with variable magnification. Delayed electron emission can be recorded in our experimental setup for any time duration after the photoexcitation of the polyatomic anions. Experiments were carried out with trapped O− and C5− ions to demonstrate the capability of the spectrometer. Delayed electron emissions from C5− as well as prompt photoelectrons from O− were detected by the VMI spectrometer upon photoexcitation. The design and performance of the spectrometer are presented in detail.

Ions in an ion bunch trapped inside an Electrostatic Ion Beam Trap (EIBT) exhibit collective oscillations within the bunch under the influence of an external driving force. These internal oscillations have been measured explicitly using a new method with a particle detector outside the EIBT. In this approach, the evolving ion bunch is monitored along the entire trap length, in contrast to the localized single point measurements that are often carried out in other techniques. In the present study, quadrupole oscillations have been measured for the first time in an EIBT along with the dipole oscillations that were measured previously. The frequency of the quadrupole oscillation is found to be about twice the dipole oscillation frequency. This is in agreement with the prediction of a theoretical model.

Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that are absent in the parent compounds. A prominent example is the appearance of highly conducting and superconducting states at the interface between LaAlO3 and SrTiO3. Here we report an emergent phenomenon at the LaMnO3/SrTiO3 interface where an antiferromagnetic Mott insulator abruptly transforms into a nanoscale inhomogeneous magnetic state. Upon increasing the thickness of LaMnO3, our scanning nanoSQUID-on-tip microscopy shows spontaneous formation of isolated magnetic nanoislands, which display thermally activated moment reversals in response to an in-plane magnetic field. The observed superparamagnetic state manifests the emergence of thermodynamic electronic phase separation in which metallic ferromagnetic islands nucleate in an insulating antiferromagnetic matrix. We derive a model that captures the sharp onset and the thickness dependence of the magnetization. Our model suggests that a nearby superparamagnetic-ferromagnetic transition can be gate tuned, holding potential for applications in magnetic storage and spintronics.

The bubble-assisted Liquid Hole Multiplier (LHM) is a recently-proposed concept for the combined detection of ionization electrons and primary scintillation photons in noble-liquid time projection chambers. The LHM comprises a perforated micro-pattern electrode (e.g. Thick Gas Electron Multiplier - THGEM, or Gas Electron Multiplier - GEM) immersed in the liquid, with a bubble of the noble gas supported underneath. Ionization electrons and scintillation-induced photoelectrons extracted from a cesium iodide photocathode drift through the electrode's holes and induce electroluminescence (EL) signals in the bubble; these are recorded by photon detectors located closely below the electrode. We present recent results in the development of LHMs, comparing the response of different electrodes to ionization and photon-induced electrons.

An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

Bubble formation in liquid xenon underneath a Thick Gaseous Electron Multiplier (THGEM) electrode immersed in liquid xenon was observed with a CCD camera. With voltage across the THGEM, the appearance of bubbles was correlated with that of electroluminescence signals induced by ionization electrons from alpha-particle tracks. This confirms recent indirect evidence that the observed photons are due to electroluminescence within a xenon vapor layer trapped under the electrode. The bubbles seem to emerge spontaneously due to heat flow from 300 K into the liquid, or in a controlled manner by locally boiling the liquid with resistive wires. Controlled bubble formation resulted in energy resolution of sigma/E approximate to 7.5% for similar to 6000 ionization electrons. The phenomenon could pave ways towards the conception of large-volume 'local dual-phase' noble-liquid TPCs.

We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating—for the first time—the feasibility of recording both primary (``S1'') and secondary (``S2'') scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium iodide photocathode on the first element; it was shown to operate stably at 180 K with gains above 105, providing high single-photon detection efficiency even in the presence of large α particle-induced S2 signals comprising thousands of photoelectrons. S1 scintillation signals were recorded with a time resolution of 1.2 ns (RMS). The energy resolution (σ/E) for S2 electroluminescence of 5.5 MeV α particles was ∼ 9%, which is comparable to that obtained in the XENON100 TPC with PMTs. The results are discussed within the context of potential GPM deployment in future multi-ton noble-liquid detectors.

In this work we discuss the mechanism behind the large electroluminescence signals observed at relatively low electric fields in the holes of a Thick Gas Electron Multiplier (THGEM) electrode immersed in liquid xenon. We present strong evidence that the scintillation light is generated in xenon bubbles trapped below the THGEM holes. The process is shown to be remarkably stable over months of operation, providing - under specific thermodynamic conditions - energy resolution similar to that of present dual-phase liquid xenon experiments. The observed mechanism may serve as the basis for the development of Liquid Hole Multipliers (LHMs), capable of producing local charge-induced electroluminescence signals in large-volume single-phase noble-liquid detectors for dark matter and neutrino physics experiments.