Direct mass measurements of exotic nuclei

The present status and recent results from direct mass measurements of exotic nuclei are presented. ISOL, in-flight, and combined facilities provide a wide variety of nuclides far-off stability covering a wide range of half-lives down to the sub-millisecond region. Modern direct mass measurements are carried out using frequency and time-of-flight techniques. The obtained accurate mass data point to nuclear-structure phenomena and serve as a basis for astrophysical and weak-interaction studies. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: c.scheidenberger@gsi.de     

Carbon clusters for absolute mass measurements at ISOLTRAP

The cyclotron frequencies of singly charged carbon clusters C_n ⁺ (n ≥ 2) were measured with the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The present limit of mass accuracy δm/m = 1.2 ^. 10^-8 and the extent of the mass-dependent systematic shift (δm/m)_sys = 1.7(0.6) ^. 10^-10/u ^. (m - m _ref) of the setup were investigated for the first time. In addition, absolute mass measurements by use of pure clusters of the most abundant carbon isotope ¹²C are now possible at ISOLTRAP. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"Present address: CERN, CH-1211 Geneva 23, Switzerland; e-mail: klaus.blaum@cern.ch     

Retrocrural masses of extramedullary hemopoiesis in beta-thalassemia

A case of extramedullary hemopoiesis in an 18-yr-old girl suffering from beta-thalassemia is reported. Extramedullary hemopoietic masses were localized apart from the paraspinal region in the retrocrural areas as well as the presacral region associated with massive destruction of the sacrum. The importance of recognition of hemopoietic masses in these regions in conditions other than hereditary hemolytic anaemias is briefly discussed.     

Fermilab top mass and modified Fritzsch mass matrices

Fritzsch like mass matrices with non-zero 22-elements both in U sector and D sector have been investigated in the context of latest data regardingm _t ^phys , |V _ub|, |V _cb|, |V _td| and |V _ts|. Unlike several other phenomenological models, the present model not only accommodates the value ofm _t ^phys in the range 150–240 GeV, encompassing the CDF and D0 values, but is also able to reproduce |V _cb| ≊0.040 and |V _ub/V_cb| = 0.08±0.02 and |V _td| is predicted to lie in the range 0.005–0.014. Further, the angles of the unitarity triangle, related to the CP-violating asymmetries, are calculated to be in the ranges −1.0⩽sin2α⩽−0.1, 0.6 ⩽sin2α⩽1.0 and 0.48⩽sin2β⩽0.56, which are in agreement with other recent calculations.     

Shell energy in the heaviest nuclei using the Green’s function oscillator expansion method

The Greens function oscillator expansion method and the generalized Strutinsky smoothing procedure are applied to shell corrections in the heaviest elements. A macroscopic-microscopic method with a finite deformed Woods-Saxon potential is used. The stability condition for the shell correction is discussed in detail and the parameters defining the smoothing procedure are carefully determined. It is demonstrated that the spurious contribution to the total binding energy due to the unphysical particle gas that appears in the standard method can be as large as 1.5 MeV for weakly bound neutron-rich superheavy nuclei, but the effect on energy differences (e.g., alpha-decay values) is fairly small.     

The symmetry energy in nuclei and in nuclear matter

We discuss to what extent information on ground-state properties of finite nuclei (energies and radii) can be used to obtain constraints on the symmetry energy in nuclear matter and its dependence on the density. The starting point is a generalized Weizs?cker formula for ground-state energies. In particular, effects from the Wigner energy and shell structure on the symmetry energy are investigated. Strong correlations in the parameter space prevent a clear isolation of the surface contribution. Use of neutron skin information improves the situation. The result of the analysis appears consistent with a rather soft density dependence of the symmetry energy in nuclear matter.     

Experimental Overview of Mass Measurements

Nuclear masses and binding energies are an important input for nuclear models, constituting strong constraints far from the β-stability valley. During the last decade, new experimental techniques for the production of exotic nuclei and the measurement of their mass were developed. The present paper gives an overview of these techniques. This revised version was published online in July 2006 with corrections to the Cover Date.     

超高效液相色谱-四极杆-飞行时间质谱法快速筛查农药制剂中非法添加的化学杀菌剂

建立了超高效液相色谱-四极杆-飞行时间质谱法(UPLC-Q-TOF MS)快速筛查农药制剂中35种非法添加化学杀菌剂的方法.农药制剂样品经甲醇超声溶解提取后,采用Zorbax C18色谱柱(100 mm×1.8 mm,2.1μm)进行分离,以0.1%甲酸-乙睛作为流动相进行梯度洗脱,采用正离子全扫描模式进行分析.在所建立的条件下,35种杀菌剂在0.2,0.4和2.0 mg/kg水平下的添加回收率为81.0%~101.3%,相对标准偏差为1.0%~4.4%.在100份样品有6份样品中筛查出添加了化学杀菌剂,并进行了含量分析.本方法分析效率高,结果准确可靠,适用于农药制剂中非法添加化学杀菌剂的定性筛查.     

Spatial‐skin effect for eigenvibrations of a thick cascade junction with ‘heavy’ concentrated masses

A spectral problem for the Laplace operator in a thick cascade junction with concentrated masses is considered. This cascade junction consists of the junction's body and a great number of ?‐alternating thin rods belonging to two classes. One class consists of rods of finite length, and the second one consists of rods of small length of order . The density of the junction is of order on the rods from the second class and outside of them. The asymptotic behavior of eigenvalues and eigenfunctions of this problem is studied as ? → 0. There exist five qualitatively different cases in the asymptotic behavior of eigenmagnitudes as ? → 0, namely the case of ‘light’ concentrated (α ∈ (0,1)), ‘middle’ concentrated (α = 1), and ‘heavy’ concentrated masses (α ∈ (1, + ∞ )) that we divide into ‘slightly heavy’ concentrated (α ∈ (1,2)), ‘intermediate heavy’ concentrated (α = 2), and ‘very heavy’ concentrated masses (α > 2). In the paper, we study in detail the influence of the concentrated masses on the asymptotic behavior if α ∈ (1,2). We construct the leading terms of asymptotic expansions both for the eigenvalues and eigenfunctions and prove the corresponding asymptotic estimates. Copyright © 2013 John Wiley & Sons, Ltd.     

Qβ measurements of 158, 159Pm , 159, 161Sm , 160-165Eu , 163Gd and 166Tb using a total absorption BGO detector

Q _β values of the neutron-rich isotopes of ^160-165Eu and ¹⁶³Gd were measured for the first time using a total absorption bismuth germanate (BGO) detector, and previously obtained data on ^{158, 159}Pm , ^{159, 161}Sm and ¹⁶⁶Tb were re-analyzed. These radioactive sources were prepared by an on-line mass separator (Tokai-ISOL) following the ²³⁸U (p,f reaction. The deduced Q _β values are the following: 6085(80)keV for ¹⁵⁸Pm , 3805(65)keV for ¹⁵⁹Sm , 5460(140)keV for ¹⁵⁹Pm , 4705(60)keV for ¹⁶⁰Eu , 5065(130)keV for ¹⁶¹Sm , 3705(60)keV for ¹⁶¹Eu , 5575(60)keV for ¹⁶²Eu , 4690(70)keV for ¹⁶³Eu , 3170(70)keV for ¹⁶³Gd , 6430(70)keV for ¹⁶⁴Eu , 5800(120)keV for ¹⁶⁵Eu , and 4695(70)keV for ¹⁶⁶Tb . Moreover, the deduced mass excesses and two-neutron separation energies ( S _2n values) were compared with those of the atomic mass evaluations and theoretical predictions.