The authors succeeded in conserving gas in monatomic state for several hours at the ultimately permissible temperature in a strong magnetic field. Under such conditions hydrogen atoms unite themselves relatively slowly, therefore gas may be considered as stable. As it follows from experimental results, monatomic hydrogen remains gaseous up to 0.08 K - the ultralow temperature at which the investigations have been carried out. These data at least preliminarily confirm an assumption that atomic hydrogen remains gaseous at absolute zero temperature, as it is predicted by the quantum theory.The authors succeeded in conserving gas in monatomic state for several hours at the ultimately permissible temperature in a strong magnetic field. Under such conditions hydrogen atoms unite themselves relatively slowly, therefore gas may be considered as stable. As it follows from experimental results, monatomic hydrogen remains gaseous up to 0.08 K - the ultralow temperature at which the investigations have been carried out. These data at least preliminarily confirm an assumption that atomic hydrogen remains gaseous at absolute zero temperature, as it is predicted by the quantum theory.

Apr 1, 19830 citations

Stable spin-polarized atomic hydrogen

Bertram M. Schwarzschild

The strong attraction between hydrogen atoms of opposite electron spin would seem to make it impossible to have stable monatomic hydrogen gas, except in interstellar space. But the force between hydrogen atoms of parallel spin is predominantly repulsive. Isaac Silvera and Jook Walraven of the University of Amsterdam have taken advantage of the absence of bound states for spin-polarized hydrogen to produce a monatomic hydrogen gas that showed no sign of reverting to ordinary H2 after almost an hour in a high magnetic field at low temperature, despite its very considerable density—more than 1016 atoms/cm3.The strong attraction between hydrogen atoms of opposite electron spin would seem to make it impossible to have stable monatomic hydrogen gas, except in interstellar space. But the force between hydrogen atoms of parallel spin is predominantly repulsive. Isaac Silvera and Jook Walraven of the University of Amsterdam have taken advantage of the absence of bound states for spin-polarized hydrogen to produce a monatomic hydrogen gas that showed no sign of reverting to ordinary H2 after almost an hour in a high magnetic field at low temperature, despite its very considerable density—more than 1016 atoms/cm3.

Physics TodayJun 1, 19802 citations

Excitation of Atomic Hydrogen.

J. Douglas Walker

Jan 1, 19700 citations

Measurement of the occupation number of metastable atoms in the hyperfine-substate β $_3$ in an atomic hydrogen beamMeasurement of the occupation number of metastable atoms in the hyperfine-substate β$_3$ in an atomic hydrogen beam

Moritz Westphal, R. Engels, Nicolas Faatz +5 more

After its discovery in 1947 by Willis Eugene Lamb and Robert C. Retherford the Lamb shift was used to create Lamb shift polarimeter to separate the $2S_{1/2}$ $\alpha_{1}$ and $\alpha_{2}$ hyperfine substates of hydrogen as well as the $\alpha_{3}$ substate of deuterium. But for a new project at the Technical University of Munich, investigation of the bound-beta decay of a neutron into a hydrogen atom and a neutrino, a Lamb shift polarimeter is needed that is also capable of separating the $\beta_{3}$ substate of hydrogen. Unfortunately, our first attempt to use a Sona transition unit to exchange the occupation numbers between $\alpha_{1}$ and $\beta_{3}$ failed, because of the unexpected complexity of the transitions in this unit [1]. The second idea of using a new kind of spinfilter which uses two radio frequencies to separate all four hyperfine substates of hydrogen also failed. Our third attempt is now to build a transition unit that can induce magnetic dipole transitions between $\alpha_{2}$ and $\beta_{3}$ as well as between $\alpha_{2}$ and $\beta_{4}$ ( $\pi$ transitions, i.e. an exchange of the occupation numbers of these states). This is a similar transition to what is used in atomic beam sources, in this case not for ground state atoms but for metastable atoms, which requires a much lower radio frequency. Another difference of this new idea is the smaller interaction time of the atoms with the photons inside the transition unit due to their much higher velocity of roughly $2\cdot10^5$ m/s compared to velocities of about $10^3$ m/s in an atomic beam source.After its discovery in 1947 by Willis Eugene Lamb and Robert C. Retherford the Lamb shift was used to create Lamb shift polarimeter to separate the $2S_{1/2}$ $\alpha_{1}$ and $\alpha_{2}$ hyperfine substates of hydrogen as well as the $\alpha_{3}$ substate of deuterium. But for a new project at the Technical University of Munich, investigation of the bound-beta decay of a neutron into a hydrogen atom and a neutrino, a Lamb shift polarimeter is needed that is also capable of separating the $\beta_{3}$ substate of hydrogen. Unfortunately, our first attempt to use a Sona transition unit to exchange the occupation numbers between $\alpha_{1}$ and $\beta_{3}$ failed, because of the unexpected complexity of the transitions in this unit [1]. The second idea of using a new kind of spinfilter which uses two radio frequencies to separate all four hyperfine substates of hydrogen also failed. Our third attempt is now to build a transition unit that can induce magnetic dipole transitions between $\alpha_{2}$ and $\beta_{3}$ as well as between $\alpha_{2}$ and $\beta_{4}$ ($\pi$ transitions, i.e. an exchange of the occupation numbers of these states). This is a similar transition to what is used in atomic beam sources, in this case not for ground state atoms but for metastable atoms, which requires a much lower radio frequency. Another difference of this new idea is the smaller interaction time of the atoms with the photons inside the transition unit due to their much higher velocity of roughly $2\cdot10^5$ m/s compared to velocities of about $10^3$ m/s in an atomic beam source.

International Workshop on Polarized Sources and Targets (PST)Mar 14, 20230 citations

Coherent Excitation of Hydrogen Atoms.

G. Gabrielse

Jan 1, 19800 citations

Measurement of the occupation number of metastable atoms in the hyperfine-substate β

_3

in an atomic hydrogen beam

After its discovery in 1947 by Willis Eugene Lamb and Robert C. Retherford the Lamb shift was used to create Lamb shift polarimeter to separate the

2S_{1/2}

\alpha_{1}

and

\alpha_{2}

hyperfine substates of hydrogen as well as the

\alpha_{3}

substate of deuterium. But for a new project at the Technical University of Munich, investigation of the bound-beta decay of a neutron into a hydrogen atom and a neutrino, a Lamb shift polarimeter is needed that is also capable of separating the

\beta_{3}

substate of hydrogen. Unfortunately, our first attempt to use a Sona transition unit to exchange the occupation numbers between

\alpha_{1}

and

\beta_{3}

failed, because of the unexpected complexity of the transitions in this unit [1]. The second idea of using a new kind of spinfilter which uses two radio frequencies to separate all four hyperfine substates of hydrogen also failed. Our third attempt is now to build a transition unit that can induce magnetic dipole transitions between

\alpha_{2}

and

\beta_{3}

as well as between

\alpha_{2}

and

\beta_{4}

(

\pi

transitions, i.e. an exchange of the occupation numbers of these states). This is a similar transition to what is used in atomic beam sources, in this case not for ground state atoms but for metastable atoms, which requires a much lower radio frequency. Another difference of this new idea is the smaller interaction time of the atoms with the photons inside the transition unit due to their much higher velocity of roughly

2\cdot10^5

m/s compared to velocities of about

10^3

m/s in an atomic beam source.