Ion counting efficiencies at the IGISOL facility

At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high precision. Fission fragments from a U target are passing through a Ni foil and entering a gas filled chamber. The collected fragments are guided through a mass separator to a Penning trap where their masses are identified. This simulation work focuses on how different fission fragment properties (mass, charge and energy) affect the stopping efficiency in the gas cell. In addition, different experimental parameters are varied (e. g. U and Ni thickness and He gas pressure) to study their impact on the stopping efficiency. The simulations were performed using the Geant4 package and the SRIM code. The main results suggest a small variation in the stopping efficiency as a function of mass, charge and kinetic energy. It is predicted that heavy fragments are stopped about 9% less efficiently than the light fragments. However it was found that the properties of the U, Ni and the He gas influences this behavior. Hence it could be possible to optimize the efficiency.Comment: 52 pages, 44 figure

Increased IGF-1: IGFBP-3 ratio in patients with hepatocellular carcinoma

BACKGROUND: The development of hepatocellular carcinoma in liver cirrhosis is associated with altered synthesis and secretion of several growth factors. AIM: The aim of this prospective study was to investigate the potential implication of IGF-I and its major binding protein (IGFBP-3) in the development of hepatocellular carcinoma. PATIENTS AND METHODS: IGF-I and IGFBP-3 were measured in 150 healthy subjects, 40 patients with liver cirrhosis and 63 with liver cirrhosis and untreated hepatocellular carcinoma. The ratio between IGF-I and IGFBP-3 was also calculated. RESULTS: Serum IGF-I (70 ± 10 and 65 ± 7 vs. 185 ± 6.4 μg/l, P < 0.001) and IGFBP-3 levels (1225 ± 113 and 984 ± 67 vs. 3017 ± 80 μg/l, P < 0.001) were lower in patients with liver cirrhosis, without or with hepatocellular carcinoma, than in controls. Age was negatively correlated with IGF-I levels In patients with liver cirrhosis (r = -0.6; P = 0.0002) as well as in controls (r = -0.8, P < 0.0001), but not in patients with hepatocellular carcinoma (r = -0.2; P = 0.2). Additionally, in patients with liver cirrhosis (r = -0.54; P = 0.0003) and more weakly in those with hepatocellular carcinoma (r = -0.24; P = 0.04) IGF-I levels were negatively correlated with liver failure measured according with Child class. Despite patients with class C hepatocellular carcinoma being older than those in the same functional class with cirrhosis (64 ± 2 vs. 57 ± 2 years, P < 0.01), they had a significantly increased IGF-I : IGFBP-3 ratio (0.18 ± 0.05 vs. 0.41 ± 0.09, P = 0.04), due mostly to increased IGF-I levels (27.1 ± 5.6 vs. 42 ± 6.2 μg/l) as IGFBP-3 levels were similar to patients with cirrhosis (734 ± 81 vs. 679 ± 83 μg/l). CONCLUSIONS: Hepatocellular carcinoma is associated with a higher IGF-I : IGFBP-3 ratio than that found in patients with liver cirrhosis and a similar degree of liver failure

Uniaxial magnetic anisotropy tuned by nanoscale ripple formation: ion-sculpting of Co/Cu(001) thin films

We have investigated the growth of surface nanostructures on a Co/Cu(001) film and the growth of Co films on a nanostructured Cu(001) substrate as well as the effect of nanoscale pattern formation on the film magnetic properties. Here we demonstrate by scanning tunneling microscopy measurements and magneto-optic Kerr effect hysteresis curves that low-temperature grazing-incidence ion sputtering can be used to induce the formation of nanoscale ripples which reduce the four-fold symmetry of the Co film to two-fold, thus generating a strong in-plane uniaxial magnetic anisotropy. The nanostructures and the associated uniaxial magnetic anisotropy were found to be stable up to room temperature

Characterization of a Be(p,xn) neutron source for fission yields measurements

We report on measurements performed at The Svedberg Laboratory (TSL) to characterize a proton-neutron converter for independent fission yield studies at the IGISOL-JYFLTRAP facility (Jyv\"askyl\"a, Finland). A 30 MeV proton beam impinged on a 5 mm water-cooled Beryllium target. Two independent experimental techniques have been used to measure the neutron spectrum: a Time of Flight (TOF) system used to estimate the high-energy contribution, and a Bonner Sphere Spectrometer able to provide precise results from thermal energies up to 20 MeV. An overlap between the energy regions covered by the two systems will permit a cross-check of the results from the different techniques. In this paper, the measurement and analysis techniques will be presented together with some preliminary results.Comment: 3 pages, 3 figures, also submitted as proceedings of the International Conference on Nuclear Data for Science and Technology 201

Imaging of metabolic bone disease

Osteoporosis is the most important metabolic bone disease, with a wide distribution among the elderly. It is characterized by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk. Identify bone weakening with an appropriate and accurate use of diagnostic imaging is of critical importance in the diagnosis and follow-up of osteoporotic patients. The aim of this review is to evaluate the detection rates of the different imaging modalities in the evaluation of bone strength, in the assessment of fracture risk and in the management of fragility fractures

Surfactant-like Effect and Dissolution of Ultrathin Fe Films on Ag(001)

The phase immiscibility and the excellent matching between Ag(001) and Fe(001) unit cells (mismatch 0.8 %) make Fe/Ag growth attractive in the field of low dimensionality magnetic systems. Intermixing could be drastically limited at deposition temperatures as low as 140-150 K. The film structural evolution induced by post-growth annealing presents many interesting aspects involving activated atomic exchange processes and affecting magnetic properties. Previous experiments, of He and low energy ion scattering on films deposited at 150 K, indicated the formation of a segregated Ag layer upon annealing at 550 K. Higher temperatures led to the embedding of Fe into the Ag matrix. In those experiments, information on sub-surface layers was attained by techniques mainly sensitive to the topmost layer. Here, systematic PED measurements, providing chemical selectivity and structural information for a depth of several layers, have been accompanied with a few XRD rod scans, yielding a better sensitivity to the buried interface and to the film long range order. The results of this paper allow a comparison with recent models enlightening the dissolution paths of an ultra thin metal film into a different metal, when both subsurface migration of the deposit and phase separation between substrate and deposit are favoured. The occurrence of a surfactant-like stage, in which a single layer of Ag covers the Fe film is demonstrated for films of 4-6 ML heated at 500-550 K. Evidence of a stage characterized by the formation of two Ag capping layers is also reported. As the annealing temperature was increased beyond 700 K, the surface layers closely resembled the structure of bare Ag(001) with the residual presence of subsurface Fe aggregates.Comment: 4 pages, 3 figure