共查询到20条相似文献,搜索用时 109 毫秒
1.
H. Penttil? P. Karvonen T. Eronen V. -V. Elomaa U. Hager J. Hakala A. Jokinen A. Kankainen I. D. Moore K. Per?j?rvi S. Rahaman S. Rinta-Antila V. Rubchenya A. Saastamoinen T. Sonoda J. ?yst? 《The European Physical Journal A - Hadrons and Nuclei》2010,44(1):147-168
A novel method to determine independent yields in particle-induced fission employing the ion guide technique and ion counting after a Penning trap has been developed. The method takes advantage of the fact that a Penning trap can be used as a precision mass filter, which allows an unambiguous identification of the fission fragments. The method was tested with 25MeV and 50MeV proton-induced fission of 238U . The data is internally reproducible with an accuracy of a few per cent. A satisfactory agreement was obtained with older ion guide yield measurements in 25MeV proton-induced fission. The results for Rb and Cs yields in 50MeV proton-induced fission agree with previous measurements performed at an isotope separator equipped with a chemically selective ion source. 相似文献
2.
V. V. Simon P. Delheij J. Dilling Z. Ke W. Shi G. Gwinner 《Hyperfine Interactions》2011,199(1-3):151-159
TITAN is an on-line facility dedicated to precision experiments with short-lived radioactive isotopes, in particular mass measurements. The achievable resolution on mass measurement, which depends on the excitation time, is limited by the half life of the radioactive ion. One way to bypass this is by increasing the charge state of the ion of interest. TITAN has the unique capability of charge-breeding radioactive ions using an electron-beam ion trap (EBIT) in combination with Penning trap mass spectrometry. However, the breeding process leads to an increase in energy spread, ??E, which in turn negatively influences the mass uncertainty. We report on the development of a cooler Penning trap which aims at reducing the energy spread of the highly charged ions prior to injection into the precision mass measurement trap. Electron and proton cooling will be tested as possible routes. Mass selective cooling techniques are also envisioned. 相似文献
3.
F. Ames P. Schmidt O. Forstner G. Bollen O. Engels D. Habs G. Huber 《Hyperfine Interactions》2001,132(1-4):465-468
The beam quality of radioactive ion beams produced by present target ion source technology is often not sufficient for direct
post-acceleration. Furthermore, pulsed beams insure a more efficient use of an accelerator. In the case of REX-ISOLDE, the
post accelerator at the CERN ISOLDE facility, a gas-filled Penning trap (REXTRAP) has been chosen for accumulation of the
radioactive ions and conversion into cooled bunches. Radial centering of the ions is achieved by applying an rf field with
a frequency equal to the cyclotron frequency of the desired ion species. The efficiency achieved in the first tests with different
isotopes covering nearly the entire mass range was already >20%. Going to total numbers of >105 stored ions in the trap a shift of the centering frequency could be observed, which is most likely due to space charge effects.
Despite this, it was possible to accumulate up to 107 ions and deliver them as cooled bunches.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
M. Diederich H. Häffner N. Hermanspahn M. Immel H.J. Kluge R. Ley R. Mann W. Quint S. Stahl G. Werth 《Hyperfine Interactions》1998,115(1-4):185-192
We describe how a single hydrogen-like ion (C5+) is prepared, cooled with the method of resistive cooling and non-destructively detected with the image-current technique
in a cryogenic Penning trap at T = 4 K. The storage time for C5+-ions in the cryogenically pumped vacuum chamber is longer than six months. The experimental techniques of preparing, cooling
and detecting highly-charged ions in a Penning trap are relevant for precision experiments such as g-factor measurements,
mass spectroscopy and laser spectroscopy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
S. Bharadia M. Vogel D. M. Segal R. C. Thompson 《Applied physics. B, Lasers and optics》2012,107(4):1105-1115
We have performed systematic measurements of the dynamics of laser-cooled 40Ca+ ions confined in a Penning trap and driven by a rotating dipole field (‘rotating wall’). The trap used is a copy of the one used in the SPECTRAP experiment located at the HITRAP facility at GSI, Germany. The size and shape of the ion cloud has been monitored using a CCD camera to image the fluorescence light resulting from excitation by the cooling laser. We have varied the experimental conditions such as amplitude and frequency of the rotating wall drive as well as the trapping parameters. The rotating wall can be used for a radial compression of the ion cloud thus increasing the ion density in the trap. We have also observed plasma mode excitations in agreement with theoretical expectations. This work will allow us to define the optimum parameters for high compression of the ions as needed for precision spectroscopy of forbidden transitions. 相似文献
6.
M. Mukherjee D. Beck K. Blaum G. Bollen J. Dilling S. George F. Herfurth A. Herlert A. Kellerbauer H. -J. Kluge S. Schwarz L. Schweikhard C. Yazidjian 《The European Physical Journal A - Hadrons and Nuclei》2008,35(1):1-29
ISOLTRAP is a Penning trap mass spectrometer for high-precision mass measurements on short-lived nuclides installed at the
on-line isotope separator ISOLDE at CERN. The masses of close to 300 radionuclides have been determined up to now. The applicability
of Penning trap mass spectrometry to mass measurements of exotic nuclei has been extended considerably at ISOLTRAP by improving
and developing this double Penning trap mass spectrometer over the past two decades. The accurate determination of nuclear
binding energies far from stability includes nuclei that are produced at rates less than 100 ions/s and with half-lives well
below 100ms. The mass-resolving power reaches 107 corresponding to 10keV for medium heavy nuclei and the uncertainty of the resulting mass values has been pushed down to below
10-8. The article describes technical developments achieved since 1996 and the present performance of ISOLTRAP. 相似文献
7.
High densities of ultra cold positrons are required for applications such as positronium production, scattering processes
with atoms, surface analysis, cooling of highly charged ions and antihydrogen production. At the University of Aarhus, Denmark,
an accelerator based slow positron source delivers about 5 × 104 positrons within a 10 ns bunch at a repetition rate of 10 Hz. The energy spread is below 1 eV and the beam diameter is about
1 mm. The positron bunches shall be injected into a 6-T Penning trap at the temperature of liquid helium. The bunches can
be captured at nearly 100% efficiency by a fast time variation of the trap potential. The cyclotron motion cools down by synchrotron
radiation with a time constant of 80 ms. The axial motion can be cooled by coupling to the radial motion or by resistive cooling
in a tuned circuit. By stacking of 100 pulses about 5 × 106 positrons can be accumulated within 10 s. After this time most of the positrons have cooled down sufficiently that the trapping
cycle can be started again. At the anticipated accumulation rate a positron plasma at the space charge limit should be obtainable
within 1 h.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
J. Szerypo V. S. Kolhinen M. Bussmann E. Gartzke D. Habs J. Neumayr U. Schramm C. Schürmann M. Sewtz P. G. Thirolf 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):319-322
The MLLTRAP at the Maier-Leibnitz-Laboratory (Garching) is a new Penning trap facility designed to combine several novel technologies
to decelerate, charge breed, cool, bunch and purify the reaction products and perform high-accuracy nuclear and atomic mass
measurements. It is now in the commissioning phase, achieving a mass-resolving power of about 105 in the purification trap for stable ions. 相似文献
9.
H. Imajo K. Hayasaka R. Ohmukai M. Watanabe S. Urabe 《Applied physics. B, Lasers and optics》1995,61(3):285-289
Be+ ions trapped in a Penning trap are laser-cooled to about 10 mK. The excitation spectra of ion clouds containing about 500 ions are obtained by scanning the frequency of the cooling laser and discontinuities in these spectra are observed because of phase transitions. When the cooled ions are heated electrically by applying an rf voltage, no phase transition occurs and the spectra become continuous. Two-dimensional measurement of the ion clouds is carried out and the abrupt change in the shape of the ion cloud due to the phase transition is observed. When many ions are trapped and cooled, the phase transition occurs partially and a transient state where two states are mixed can be observed. The static properties of the ions are also measured by using an additional probe laser and the results of experimental measurements are compared with theoretical predictions. 相似文献
10.
P. Delheij L. Blomeley M. Froese G. Gwinner V. Ryjkov M. Smith J. Dilling 《Hyperfine Interactions》2006,173(1-3):123-131
The TITAN facility at TRIUMF-ISAC will use four ion traps with the primary goal of determining nuclear masses with high precision, particularly for short lived isotopes with lifetimes down to approximately 10 ms. The design value for the accuracy of the mass measurement is 1 ×10???8. The four main components in the facility are an RF cooler/buncher (RFCT) receiving the incoming ion beam, an electron beam ion trap (EBIT) to breed the ions to higher charge states, a cooler Penning trap (CPET) to cool the highly charged ions, and finally the measurement Penning trap (MPET) for the precision mass determination. Additional goals for this system are laser spectroscopy on ions extracted from the RFCT and beta spectroscopy in the EBIT (in Penning trap mode) on ions that are purified using selective buffer gas cooling in the CPET. The physics motivation for the mass measurements are manifold, from unitarity tests of the CKM matrix to nuclear structure very far from the valley of stability, nuclear astrophysics and the study of halo-nuclei. As a first measurement the mass of 11Li will be determined. With a lifetime of 8.7 ms and a demonstrated production rate of 4×104 ions/sec at ISAC the goal for this measurement at TITAN is a relative uncertainty of 5×10???8. This would check previous conflicting measurements and provide information for nuclear theory and models. 相似文献
11.
T. Fritioff C. Carlberg G. Douysset R. Schuch I. Bergström 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):141-143
The atomic and nuclear masses of 4He and 3He have been measured using doubly charged ions in a Penning trap connected to an electron beam ion source. Recent technical
improvements allow mass determinations with uncertainties of a few parts in 1010. The obtained atomic masses are 4.002 603 256 8(13) u and 3.016 029 323 5(28) u respectively. These values deviate by as
much as 5 standard deviations from the accepted values.
Received 23 October 2000 and Received in final form 6 February 2001 相似文献
12.
S. Schwarz M. Block G. Bollen C. M. Campbell M. Facina R. Ferrer C. M. Folden III A. A. Kwiatkowski D. J. Morrissey G. K. Pang A. M. Prinke R. J. Ringle J. Savory P. H. Schury 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):323-326
The low-energy beam and ion trap facility LEBIT at NSCL/MSU is at present the only facility where precision experiments are performed with stopped rare isotope beams produced by fast-beam fragmentation. LEBIT combines high-pressure-gas stopping with advanced ion manipulation techniques to provide brilliant low-energy beams. So far these beams have mainly been used for mass measurements on short-lived rare isotopes with a 9.4T Penning trap mass spectrometer. Recent examples include 70m Br , located at the proton dripline, 32Si and the iron isotopes 63-65Fe . While the measurement of 32Si helps to solve a long-standing dispute over the validity of the isobaric multiplet mass equation (IMME) for the A = 32 , T = 2 multiplet, the mass measurements of 65m,g Fe marked the first time a nuclear isomeric state has been discovered by Penning trap mass spectrometry. 相似文献
13.
The excitation of the motion of ions in a Penning trap at twice their cyclotron frequency, 2ν
c
, by means of an azimuthal octupolar RF field has been studied with the LEBIT facility at the NSCL. The possibility of such
an RF octupolar excitation has been verified. Compared to ion excitation at ν
c
by means of quadrupolar fields an increased resolving power is observed in the cyclotron resonance curves, which may have
important implications for Penning trap mass measurements. Numerical simulations have been used to characterize important
properties of this type of excitation in detail and to predict the behavior of the ion motion under realistic conditions.
Good agreement with the experimental results is observed.
相似文献
14.
H. Imajo S. Urabe K. Hayasaka M. Watanabe R. Hayashi 《Applied physics. B, Lasers and optics》1993,57(2):141-144
Be+ ions stored in a Penning trap were cooled by a laser beam perpendicular to the magnetic field. The cooled ions are strongly coupled and phase transitions of up to 100 ions were observed. In experiments with only a few ions stored in the trap, a stepwise decrease in fluorescence intensity was observed. All steps are of the same size and so every step is attributed to a single ion. The discrete changes in fluorescence occurred more frequently when the background pressure was increased, caused by collisions between stored ions and background neutral molecules. 相似文献
15.
We describe a laser-cooling experiment on Mg+ ions confined in an electromagnetic trap (Penning trap or rf trap) and give the preliminary experimental results. In particular, we have observed a laser cooling in the Penning trap configuration in which a measured temperature of about 1 K has been obtained. 相似文献
16.
T. Schwarz R. Jertz J. Stein I. Bergström H. Borgenstrand C. Carlberg G. Rouleau R. Schuch F. Söderberg G. Bollen H. -J. Kluge R. Mann 《Hyperfine Interactions》1996,99(1):83-89
In the SMILETRAP facility externally produced highly charged ions are captured in a Penning trap and utilized for high precision measurements of atomic masses. Accuracy tests on a ppb level have been performed, using highly charged carbon, oxygen and neon ions. In all cases hydrogen ions served as a reference for the calibration and monitoring of the magnetic field in the trap. Deviations smaller than 3 ppb from the expected results were found in mass measurements of the16O and20Ne atomic masses. The proton atomic mass, determined from the reference measurements on hydrogen ions, is in good agreement with the accepted value [1]. A direct mass measurement on the86Kr-isotope, using trapped86Kr29+-ions is reported. 相似文献
17.
We describe the construction of a novel compact Penning trap from strong permanent magnets for trapping light ions. Our cylindrically symmetric, iron-free magnetic configuration allows fully analytical treatment, is easy to handle and to optimize. The magnetic field inhomogeneity is less than 1% in a volume of 1 cm3 at 0.7 T. The stored H+ and H
2
+
ions in this trap are detected electrically by the rf absorption method. The charge density, total number and storage time of the trapped ions are measured.Dedicated to H. Walther on the occasion of his 60th birthday 相似文献
18.
For the determination of the bound-electron g factor
in hydrogen-like heavy ions the mass of the ion is needed at a
relative uncertainty of at least 1 ppb. With the
SMILETRAP Penning trap mass spectrometer at the Manne
Siegbahn Laboratory in Stockholm several mass measurements of ions
with even-even nuclei at this level of precision have been
performed so far, exploiting the fact that the mass precision
increases linearly with the ion charge. Measurements of masses of
the hydrogen-like ions of the two Mg-isotopes 24Mg and
26Mg are reported. The masses of the hydrogen-like ions are
23.979011054(14) u and 25.976562354(34) u,
corresponding to the atomic masses 23.985041690(14) u and
25.982592986(34) u, respectively. The possibility to use
these two isotopes for the first observation of an isotope effect
in the bound-electron g factor in hydrogen-like heavy ions is
discussed. 相似文献
19.
Externally, in an electron beam ion trap, generated Ar16+ ions were retrapped in a Penning trap and evaporatively cooled in their axial motion. The cooling was observed by a novel extraction technique based on the excitation of a coherent axial oscillation which yields short ion bunches of well-defined energies. The initial temperature of the ion cloud was decreased by a factor of more than 140 within 1?s, while the phase-space density of the coldest extracted ion pulses was increased by a factor of up to about 9. 相似文献
20.
Positrons from a 12 mCi22Na source are slowed by a W(110) reflection moderator and then captured in a Penning trap, by damping their motion with a tuned circuit. Because of the stability of the Penning trap and the cryogenic ultra-high vacuum environment, we anticipate that positrons can be accumulated and stored indefinitely. A continuous loading rate of 0.14 e+/s is observed for 32 h in this initial demonstration. More than 1.6×104 positrons have thus been trapped and stored at 4 K, with improvements expected. The extremely high vacuum is required for compatibility with an existing antiproton trap, which has already held more than 105 antiprotons at 4 K, for producing antihydrogen at low temperatures. The extremely cold positrons in high vacuum may also prove to be useful for cooling highly stripped ions. 相似文献