A. Lapierre

Publications (72)75.91 Total impact

• Article: Status of the EBIT in the ReA3 reaccelerator at NSCL

  S. Schwarz, G. Bollen, M. Doleans, O. Kester, K. Kittimanapun, M. Kostin, A. Lapierre, M. Portillo, C. Wilson, J. R. Crespo López-Urrutia, J. Dilling
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  ABSTRACT: At the NSCL a reaccelerator with design end energy of 3 MeV/u for 238U, called ReA3, is approaching the end of construction. ReA3 will be coupled to a gas stopper at the NSCL fragmentation facility to provide rare-isotope beams of nuclides not available at ISOL facilities in this energy range. An Electron Beam Ion Trap (EBIT) will be used to provide highly charged ions at an energy of about 12 keV/u. The charge breeder is followed by a room-temperature radiofrequency quadrupole (RFQ) and a series of superconducting linear accelerator structures. Initial commissioning results from the EBIT and its charge-over-mass separator are presented. KeywordsCharge breeding–EBIS–EBIT–Radioactive isotopes–Reacceleration
  Hyperfine Interactions 04/2012; 199(1):261-267. · 0.21 Impact Factor
• Article: In-trap decay spectroscopy for 2νββ decay experiments

  T. Brunner, M. Brodeur, P. Delheij, S. Ettenauer, D. Frekers, A. T. Gallant, R. Krücken, A. Lapierre, D. Lunney, R. Ringle, V. V. Simon, J. Dilling
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  ABSTRACT: Knowledge of 2νββ nuclear matrix elements is essential to probe the theoretical framework of 0νββ decays. At TITAN, TRIUMF’s Ion Trap for Atomic and Nuclear science, a novel technique has been developed to measure electron capture branches of virtual intermediate nuclei in ββ decays. During two experiments with radioactive 124, 126Cs isotopes the feasibility of this new method was proven. KeywordsElectron capture branching ratio–Neutrinoless double beta decay–In-trap-decay spectroscopy
  Hyperfine Interactions 04/2012; 199(1):191-199. · 0.21 Impact Factor
• Article: Precision mass measurements of neutron halo nuclei using the TITAN Penning trap

  M. Brodeur, T. Brunner, S. Ettenauer, A. T. Gallant, V. V. Simon, M. Smith, A. Lapierre, E. Mané, R. Ringle, V. L. Ryjkov, S. Bacca, P. Delheij, D. Lunney, M. Pearson, J. Dilling
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  ABSTRACT: Precise atomic mass determinations play a key role in various fields of physics, including nuclear physics, testing of fundamental symmetries and constants and atomic physics. Recently, the TITAN Penning trap measured the masses of several neutron halos. These exotic systems have an extended, diluted, matter distribution that can be modelled by considering a nuclear core surrounded by a halo formed by one or more of loosely bound neutrons. Combined with laser spectroscopy measurements of isotopic shifts precise masses can be used to obtain reliable charge radii and two-neutron-seperation energies for these halo nuclei. It is shown that these results can be used as stringent tests of nuclear models and potentials providing an important metric for our understanding of the interactions in all nuclei. KeywordsHalo nuclei–Penning trap–Mass measurement–Nuclear theory
  Hyperfine Interactions 04/2012; 199(1):167-173. · 0.21 Impact Factor
• Article: Elucidation of the anomalous A = 9 isospin quartet behaviour

  M. Brodeur, T. Brunner, S. Ettenauer, A. Lapierre, R. Ringle, B. A. Brown, D. Lunney, J. Dilling
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  ABSTRACT: Recent high-precision mass measurements of $^{9}$Li and $^{9}$Be, performed with the TITAN Penning trap at the TRIUMF ISAC facility, are analyzed in light of state-of-the-art shell model calculations. We find an explanation for the anomalous Isobaric Mass Multiplet Equation (IMME) behaviour for the two $A$ = 9 quartets. The presence of a cubic $d$ = 6.3(17) keV term for the $J^{\pi}$ = 3/2$^{-}$ quartet and the vanishing cubic term for the excited $J^{\pi}$ = 1/2$^{-}$ multiplet depend upon the presence of a nearby $T$ = 1/2 state in $^{9}$B and $^{9}$Be that induces isospin mixing. This is contrary to previous hypotheses involving purely Coulomb and charge-dependent effects. $T$ = 1/2 states have been observed near the calculated energy, above the $T$ = 3/2 state. However an experimental confirmation of their $J^{\pi}$ is needed.
  04/2012;
• Source

  Available from: Thomas Brunner

  Article: First direct mass measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He.

  M Brodeur, T Brunner, C Champagne, S Ettenauer, M J Smith, A Lapierre, R Ringle, V L Ryjkov, S Bacca, P Delheij, G W F Drake, D Lunney, A Schwenk, J Dilling
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  ABSTRACT: The first direct mass measurement of {6}He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of {8}He was determined with improved precision over our previous measurement. The obtained masses are m({6}He)=6.018 885 883(57)  u and m({8}He)=8.033 934 44(11)  u. The {6}He value shows a deviation from the literature of 4σ. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16) fm for {6}He and {8}He, respectively. We present a detailed comparison to nuclear theory for {6}He, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces.
  Physical Review Letters 02/2012; 108(5):052504. · 7.37 Impact Factor
• Article: The on-line charge breeding program at TRIUMF's Ion Trap For Atomic and Nuclear Science for precision mass measurements.

  M C Simon, J C Bale, U Chowdhury, B Eberhardt, S Ettenauer, A T Gallant, F Jang, A Lennarz, M Luichtl, T Ma, [......], D Frekers, A Grossheim, G Gwinner, A A Kwiatkowski, A Lapierre, E Mané, M R Pearson, R Ringle, B E Schultz, J Dilling
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  ABSTRACT: TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) constitutes the only high precision mass measurement setup coupled to a rare isotope facility capable of increasing the charge state of short-lived nuclides prior to the actual mass determination in a Penning trap. Recent developments around TITAN's charge breeder, the electron beam ion trap, form the basis for several successful experiments on radioactive isotopes with half-lives as low as 65 ms and in charge states as high as 22+.
  The Review of scientific instruments 02/2012; 83(2):02A912. · 1.52 Impact Factor
• Article: Initial commissioning results with the NSCL Electron Beam Ion Trap.

  S Schwarz, G Bollen, J R Crespo López-Urrutia, O Kester, K Kittimanapun, A Lapierre, D Leitner, J Ottarson, M Portillo
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  ABSTRACT: The ReA reaccelerator is being added to the National Superconducting Cyclotron Laboratory (NSCL) fragmentation facility in order to provide exotic rare-isotope beams, not available at the Isotope Separation On-Line facilities, in the several-MeV/u energy range. The first stage of the NSCL reaccelerator complex, consisting of an EBIT charge breeder, a room-temperature radiofrequency quadrupole (RFQ) accelerator, and superconducting linear accelerator modules, has been completed and is being put into operation. Commissioning of the EBIT has started by extracting charge-bred residual gas ions, ions created from a Ne gas jet directed across the EBIT's electron beam and ions captured from an external test ion source. Charge-bred ions from the Ne gas jet have been extracted as a pulse and accelerated through the RFQ and the two cryomodules.
  The Review of scientific instruments 02/2012; 83(2):02A908. · 1.52 Impact Factor
• Article: Elucidation of the Anomalous A=9 Isospin Quartet Behavior

  M Brodeur, T Brunner, S Ettenauer, A Lapierre, R Ringle, B A Brown, D Lunney, J Dilling
  Physical Review Letters 01/2012; 108(21):212501-. · 7.37 Impact Factor
• Source

  Available from: Corina Andreoiu

  Article: First use of high charge states for mass measurements of short-lived nuclides in a Penning trap.

  S Ettenauer, M C Simon, A T Gallant, T Brunner, U Chowdhury, V V Simon, M Brodeur, A Chaudhuri, E Mané, C Andreoiu, G Audi, J R Crespo López-Urrutia, P Delheij, G Gwinner, A Lapierre, D Lunney, M R Pearson, R Ringle, J Ullrich, J Dilling
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  ABSTRACT: Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed β emitter 74Rb (T(1/2)=65  ms). The determination of its atomic mass and an improved Q(EC) value are presented.
  Physical Review Letters 12/2011; 107(27):272501. · 7.37 Impact Factor
• Source

  Available from: Thomas Brunner

  Article: Penning-Trap Mass Measurements of the Neutron-Rich K and Ca Isotopes: Resurgence of the N = 28 Shell Strength

  A. Lapierre, M. Brodeur, T. Brunner, S. Ettenauer, P. Finlay, A. T. Gallant, V. V. Simon, P. Delheij, D. Lunney, R. Ringle, H. Savajols, J. Dilling
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  ABSTRACT: We present Penning-trap mass measurements of neutron-rich 44,47-50K and 49,50Ca isotopes carried out at the TITAN facility at TRIUMF-ISAC. The 44K mass measurement was performed with a charge-bred 4+ ion utilizing the TITAN EBIT, and agrees with the literature. The mass excesses obtained for 47K and 49,50Ca are more precise and agree with the values published in the 2003 Atomic Mass Evaluation (AME'03). The 48,49,50K mass excesses are more precise than the AME'03 values by more than one order of magnitude. For 48,49K, we find deviations by 7 sigma and 10 sigma, respectively. The new 49K mass excess lowers significantly the two-neutron separation energy at the neutron number N=30 compared with the separation energy calculated from the AME'03 mass-excess values, and thus, increases the N=28 neutron-shell gap energy at Z=19 by approximately 1 MeV.
  11/2011;
• Source

  Available from: Thomas Brunner

  Article: Verifying the accuracy of the TITAN Penning-trap mass spectrometer

  M. Brodeur, V. L. Ryjkov, T. Brunner, S. Ettenauer, A. T. Gallant, V. V. Simon, M. J. Smith, A. Lapierre, R. Ringle, P. Delheij, M. Good, D. Lunney, J. Dilling
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  ABSTRACT: TITAN (TRIUMF's Ion Traps for Atomic and Nuclear science) is an online facility designed to carry out high-precision mass measurements on singly and highly charged radioactive ions. The TITAN Penning trap has been built and optimized in order to perform such measurements with an accuracy in the sub ppb-range. A detailed characterization of the TITAN Penning trap is presented and a new compensation method is derived and demonstrated, verifying the performance in the range of sub-ppb.
  10/2011;
• Article: Design of a β-detector for TITAN-EC and the first electron-capture branching ratio measurement in a Penning trap

  T Brunner, M Brodeur, S Ettenauer, A T Gallant, R Gernhäuser, A Lapierre, R Ringle, S K L Sjue, P Delheij, D Frekers, R Krücken, K Zuber, J Dilling
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  ABSTRACT: At TRIUMF's ion trap for atomic and nuclear science (TITAN) a new experimental technique is being developed to measure electron-capture branching ratios of intermediate nuclei in double-β decays. The key feature of this novel technique is the use of an open access Penning trap. Radioactive ions are stored inside the trap while their decays are observed. X-rays following an electron capture are detected by x-ray detectors radially installed around the trap. Electrons originating from β-decays are guided out of the trap by the Penning trap's strong magnetic field where they are then detected by a Si-detector. Detailed simulations have been performed to determine the size and characterize the efficiency of this detector. During a beam time with radioactive 107In this β-detector has been used and for the first time an electron capture branching ratio has been determined with this novel technique of in-trap decay spectroscopy.
  Journal of Physics Conference Series 09/2011; 312(7):072006.
• Article: Status of the EBIT in the ReA3 reaccelerator at NSCL

  S. Schwarz, G. Bollen, M. Doleans, O. Kester, K. Kittimanapun, M. Kostin, A. Lapierre, M. Portillo, C. Wilson, J.R.C. López-Urrutia, J. Dilling
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  ABSTRACT: Export Date: 23 October 2011, Source: Scopus, CODEN: HYIND, doi: 10.1007/s10751-011-0321-9
  Hyperfine Interactions. 01/2011; 199:261-267.
• Article: MATS and LaSpec: High-precision experiments using ion traps and lasers at FAIR

  Daniel Rodríguez, Klaus Blaum, Wilfried Nörtershäuser, M. Ahammed, A. Algora, Georges Audi, J. Äystö, Dietrich Beck, M. Bender, J Billowes, [......], P. Van Duppen, A. Vasiliev, G. Vorobjev, C Weber, Klaus Wendt, M Winkler, Deyan Yordanov, F Ziegler, T. Brunner, A. Krieger
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  ABSTRACT: Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique “fingerprint”. Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10−5 to below 10−8 for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for precision measurements on rare isotopes. The technique has the potential to provide high accuracy and sensitivity even for very short-lived nuclides. Furthermore, ion traps can be used for precision decay studies and offer advantages over existing methods. With MATS (Precision Measurements of very short-lived nuclei using an A_dvanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10−9 can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. This accuracy limit is important for fundamental interaction tests, but also allows for the study of the fine structure of the nuclear mass surface with unprecedented accuracy, whenever required. The use of the FT-ICR technique provides true single ion sensitivity. This is essential to access isotopes that are produced with minimum rates which are very often the most interesting ones. Instead of pushing for highest accuracy, the high charge state of the ions can also be used to reduce the storage time of the ions, hence making measurements on even shorter-lived isotopes possible. Decay studies in ion traps will become possible with MATS. Novel spectroscopic tools for in-trap high-resolution conversion-electron and charged-particle spectroscopy from carrier-free sources will be developed, aiming e.g. at the measurements of quadrupole moments and E0 strengths. With the possibility of both high-accuracy mass measurements of the shortest-lived isotopes and decay studies, the high sensitivity and accuracy potential of MATS is ideally suited for the study of very exotic nuclides that will only be produced at the FAIR facility.Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The dependencies of the hyperfine splitting and isotope shift on the nuclear moments and mean square nuclear charge radii are well known and the theoretical framework for the extraction of nuclear parameters is well established. These extracted parameters provide fundamental information on the structure of nuclei at the limits of stability. Vital information on both bulk and valence nuclear properties are derived and an exceptional sensitivity to changes in nuclear deformation is achieved. Laser spectroscopy provides the only mechanism for such studies in exotic systems and uniquely facilitates these studies in a model-independent manner.The accuracy of laser-spectroscopic-determined nuclear properties is very high. Requirements concerning production rates are moderate; collinear spectroscopy has been performed with production rates as few as 100 ions per second and laser-desorption resonance ionization mass spectroscopy (combined with β-delayed neutron detection) has been achieved with rates of only a few atoms per second.This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy, which will provide a complete system with respect to the physics and isotopes that can be studied. Since MATS and LaSpec require high-quality low-energy beams, the two collaborations have a common beamline to stop the radioactive beam of in-flight produced isotopes and prepare them in a suitable way for transfer to the MATS and LaSpec setups, respectively.
  The European Physical Journal Special Topics 05/2010; 183:1. · 1.56 Impact Factor
• Article: Precision ground state mass of^{12} Be and an isobaric multiplet mass equation (IMME) extrapolation for 2^{+} and 0_ {2}^{+} states in the T= 2, A= 12 multiplet

  S. Ettenauer, M. Brodeur, T. Brunner, A. T. Gallant, A. Lapierre, R. Ringle, M. R. Pearson, P. Delheij, J. Lassen, D. Lunney, J. Dilling
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  ABSTRACT: We report the mass measurement of the short-lived 12Be nuclide (T1/2=21.5 ms) performed using the Penning trap mass spectrometer TITAN at TRIUMF. Our mass excess value of 25 078.0(2.1) keV is in agreement with previous measurements, but is a factor of 7 more precise than the Atomic Mass Evaluation of 2003. To address an unresolved discussion on the spin assignment of isospin T=2 states in 12C and 12O, we reevaluate the isobaric mass multiplet equation for the lowest lying T=2 multiplet in the A=12 system and use the extracted parameters to extrapolate from the known excited 2+ and 0+ states in 12Be. Though this analysis favors the second known T=2 state in 12C to be 2+, 0+ cannot be excluded.
  Phys. Rev. C. 02/2010; 81(2).
• Article: The TITAN EBIT charge breeder for mass measurements on highly charged short-lived isotopes--First online operation

  A. Lapierre, M. Brodeur, T. Brunner
  Nuclear Instruments and …. 01/2010;
• Article: Experimental investigations of ion charge distributions, effective electron densities, and electron-ion cloud overlap in electron beam ion trap plasma using extreme-ultraviolet spectroscopy

  G.Y. Liang, J.R. Crespo López-Urrutia, T.M. Baumann, S.W. Epp, A. Gonchar, A. Lapierre, P.H. Mokler, M.C. Simon, H. Tawara, V. MäcKel, K. Yao, G. Zhao, Y. Zou, J. Ullrich
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  ABSTRACT: Cited By (since 1996): 7, Export Date: 23 October 2011, Source: Scopus, doi: 10.1088/0004-637X/702/2/838
  Astrophysical Journal Letters. 01/2009; 702:838-850.
• Source

  Available from: ArXiv

  Article: Variation of the Fine-Structure Constant and Laser Cooling of Atomic Dysprosium

  N. A. Leefer, A. Cingöz, D. Budker, S. J. Ferrell, V. V. Yashchuk, A. Lapierre, A. -T. Nguyen, S. K. Lamoreaux, J. R. Torgerson
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  ABSTRACT: Radio-frequency electric-dipole transitions between nearly degenerate, opposite parity levels of atomic dysprosium (Dy) were monitored over an eight-month period to search for a variation in the fine-structure constant, $\alpha$. The data provide a rate of fractional temporal variation of $\alpha$ of $(-2.7\pm2.6)\times 10^{-15}$ yr$^{-1}$ or a value of $(-8.7 \pm 6.6) \times 10^{-6}$ for $k_\alpha$, the variation coefficient for $\alpha$ in a changing gravitational potential. All results indicate the absence of significant variation at the present level of sensitivity. We also present initial results on laser cooling of an atomic beam of dysprosium.
  12/2008;
• Article: First Penning-trap mass measurement of the exotic halo nucleus 11Li.

  M Smith, M Brodeur, T Brunner, S Ettenauer, A Lapierre, R Ringle, V L Ryjkov, F Ames, P Bricault, G W F Drake, P Delheij, D Lunney, F Sarazin, J Dilling
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  ABSTRACT: In this Letter, we report a new mass for 11Li using the trapping experiment TITAN at TRIUMF's ISAC facility. This is by far the shortest-lived nuclide, t_{1/2}=8.8 ms, for which a mass measurement has ever been performed with a Penning trap. Combined with our mass measurements of ;{8,9}Li we derive a new two-neutron separation energy of 369.15(65) keV: a factor of 7 more precise than the best previous value. This new value is a critical ingredient for the determination of the halo charge radius from isotope-shift measurements. We also report results from state-of-the-art atomic-physics calculations using the new mass and extract a new charge radius for 11Li. This result is a remarkable confluence of nuclear and atomic physics.
  Physical Review Letters 12/2008; 101(20):202501. · 7.37 Impact Factor
• Article: A laboratory search for variation of the fine-structure constant using atomic dysprosium

  A. Cingöz, N. A. Leefer, S. J. Ferrell, A. Lapierre, A.-T Nguyen, V. V. Yashchuk, D. Budker, S. K. Lamoreaux, J. R. Torgerson
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  ABSTRACT: Electric-dipole transitions between nearly degenerate, opposite parity levels of atomic dysprosium (Dy) were monitored overan eight-month period to search for a variation in thefine-structure constant, α. The frequencies of thesetransitions are sensitive to variation of α due to largerelativistic corrections of opposite sign for the opposite-paritylevels. In this unique system, in contrast to atomic-clockcomparisons, the difference of the electronic energies of theopposite-parity levels can be monitored directly utilizing aradio-frequency (rf), electric-dipole transition between them. Ourmeasurements for the frequency variation of the 3.1-MHz transitionin 163Dy and the 235-MHz transition in 162Dy can beanalyzed for both a temporal variation and a gravitational-potentialdependence of α since, during the data acquisition period, the Earth is located at different values of the gravitationalpotential of the Sun. The data provide a rate of fractional temporalvariation of α of (-2.7±2.6)×10-15yr-1 ora value of (-8.7 ±6.6) ×10-6 for kα, thelinear-variation coefficient for α in a changinggravitational potential. These results are independent ofassumptions regarding variation of other fundamental constants. Thelatter result can be combined with other experimental constraints toextract the first limits on ke and kq, which characterize thevariation of me/mp and mq/mp in a changing gravitationalpotential, where me, mp, and mq are electron, proton, andquark masses. All results indicate the absence of significantvariation at the present level of sensitivity.
  The European Physical Journal Special Topics 09/2008; 163(1):71-88. · 1.56 Impact Factor