91 research outputs found
Durability of targets and foils in experiments on synthesis of superheavy nuclei
Durability of targets and window foils irradiated by intense heavy ion (HI) beams in the experiments on synthesis of superheavy nuclei (SHN), which are carried out in Dubna with a Gas-Filled Recoil Separator (DGFRS), has been considered. High fluxes of HIs and heat generated within relatively small areas and thicknesses of the target and foils are inherent in such long-term experiments. The
ability of these elements to withstand radiation damages, sputtering and evaporation of atoms becomes questionable. All the processes are influenced by the target (foil) temperature and none of them is independent of the others, but they can be considered separately. Thus, sputtering yields were approximated on the grounds of available models and experimental data and compared to the results of measurements carried out to verify the estimates. The temperature of the target (foil), in turn, was estimated in the conditions of pulse heating followed by subsequent cooling with a radiation emitted from their surfaces. These conditions correspond to the rotating target and window irradiated by a continuous HI beam in the DGFRS experiments. Estimates show that radiative cooling might be the most effective way of heat removal at the temperature of few hundred Celsius degrees
Charge distributions of Ra recoil ions produced in 12C+Pb fusion-evaporation reactions
Charge state distributions of the Ra recoil ions produced in the 12C+Pb fusion-evaporation reactions have been obtained by measuring their yields as a function of the high voltage applied to an electrostatic deflector. Well-defined two-humped yield curves for evaporation residues (ERs) were observed. Such observations can be explained by the different sets of charge states inherent in Ra recoil ions. These charge sets correspond to the equilibrated and nonequilibrated components, as earlier observed for evaporation residues produced in different reactions. The main parameters of the distributions (mean charge values, widths, and relative intensities) for both components have been estimated using Monte Carlo simulations of the transmission of the Ra recoil ions through the deflector. For the equilibrated component the values of the mean charge and width are close to those given by different empirical systematics. For the nonequilibrated component these parameters have been obtained for the first time. The additional nonequilibrated ionization is presumably due to the formation of inner shell vacancies produced by the internal conversion of nuclear isomeric transitions of ERs. Nonequilibrated charge parameters obtained for Ra recoil ions are compared to similar available experimental data and some theoretical predictions
Investigation of the quasifission process by theoretical analysis of experimental data of fissionlike reaction products
The fusion excitation function is the important quantity in planning
experiments for the synthesis of superheavy elements. Its values seem to be
determined by the experimental study of the hindrance to complete fusion by the
observation of mass, angular and energy distributions of the fissionlike
fragments. There is ambiguity in establishment of the reaction mechanism
leading to the observed binary fissionlike fragments. The fissionlike fragments
can be produced in the quasifission, fast fission, and fusion-fission processes
which have overlapping in the mass (angular, kinetic energy) distributions of
fragments. The branching ratio between quasifission and complete fusion
strongly depends on the characteristics of the entrance channel. In this paper
we consider a wide set of reactions (with different mass asymmetry and mass
symmetry parameters) with the aim to explain the role played by many quantities
on the reaction mechanisms. We also present the results of study of the
Ca+Bk reaction used to synthesize superheavy nuclei with Z = 117
by the determination of the evaporation residue cross sections and the
effective fission barriers of excited nuclei formed along the
de-excitation cascade of the compound nucleus.Comment: 21 pages, 15 figures, 2 table
Competition of fusion and quasi-fission in the reactions leading to production of the superheavy elements
The mechanism of fusion hindrance, an effect observed in the reactions of
cold, warm and hot fusion leading to production of the superheavy elements, is
investigated. A systematics of transfermium production cross sections is used
to determine fusion probabilities. Mechanism of fusion hindrance is described
as a competition of fusion and quasi-fission. Available evaporation residue
cross sections in the superheavy region are reproduced satisfactorily. Analysis
of the measured capture cross sections is performed and a sudden disappearance
of the capture cross sections is observed at low fusion probabilities. A
dependence of the fusion hindrance on the asymmetry of the projectile-target
system is investigated using the available data. The most promising pathways
for further experiments are suggested.Comment: 8 pages, 7 figures, talk presented at 7th International
School-Seminar on Heavy-Ion Physics, May 27 - June 1, 2002, Dubna, Russi
The use of {99m}Tc-Al[2]O[3] for detection of sentinel lymph nodes in cervical cancer patients
The purpose of the study was to evaluate the feasibility of using {99m}Tc-Al[2]O[3]- based radiopharmaceutical, a novel molecular imaging agent for sentinel lymph node detection in patients with invasive cervical cancer. The study included 23 cervical cancer patients (TlaNxMx- T[2]bNxMx) treated at the Tomsk Cancer Research Institute. At 18 hours before surgery, 80 MBq of the {99m}Tc-Al[2]O[3] were injected peritumorally, followed by single-photon emission computed tomography (SPECT) of the pelvis and intraoperative SLN identification. Twenty-seven SLNs were detected by SPECT, and 34 SLNs were identified by intraoperative gamma probe. The total number of identified SLNs per patient ranged from 1 to 3(the mean number of SLNs was 1.4 per patient). The most common site for SLN detection was the external iliac region (57.2%), followed by the internal iliac, obturator, presacral and retrosacral regions (they amounted to 14%, respectively),and the parametrial region (1%). Sensitivity in detecting SLNs was 100% for intraoperative SLN identification and 79% for SPECT image
ΠΠΏΡΡ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΡΠ΅ΡΠ΅ΠΎΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π»ΡΡΠ΅Π²ΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ ΠΏΡΠΈ ΠΎΠ»ΠΈΠ³ΠΎΠΌΠ΅ΡΠ°ΡΡΠ°Π·Π°Ρ ΠΊΠΎΠ»ΠΎΡΠ΅ΠΊΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΠΊΠ° Π² ΠΏΠ΅ΡΠ΅Π½ΠΈ
Introduction: The problem of treating patients with unresectable liver metastases of colon cancer is currently far f rom being solved. One possible approach is the use of stereotactic body radiotherapy.The purpose of this study was to evaluate the immediate and long-term results of stereotactic radiotherapy in patients with colorectal cancer and oligometastatic liver metastases.Methods: This study was designed as a retro-prospective, open-label, controlled, non-randomized clinical trial. We assessed one-year local control, one-year overall survival, progression-free survival, and toxicity in 60 patients with oligometastatic liver disease from colorectal cancer who underwent stereotactic body radiotherapy, with median dose of 54 Gy.Results: The median follow-up was 20,1 months. One-year local control (LC) was 73,7 % (95 % CI = 62,7β86,6 %). Oneyear overall survival (OS) was 92,8 % (95 % CI = 86,3β99,9 %), one-year progression-free survival (PFS) was 31,3 % (95 % CI = 21,1β46,4 %) with a median of 8,1 months. Grade β₯ 3 toxicity was not noted. No cases of radiation-induced liver failure were observed. Radiation dose (HR = 0.88, 95 % CI = 0.81β0.95, p = 0.00087), metastasis size (HR = 1.51, 95 % CI = 1.07β2.12, p = 0.01858) and their number (HR = 1.8, 95 % CI = 1.01β3.22, p = 0.04669) are significant risk factors for LC. Metastasis size > 3 cm is a significant risk factor for LC (HR = 5.5, 95 % CI = 1.7β17.9, p = 0.005) and OS (HR = 3.8, 95 % CI = 1.3β11.7, p = 0.02).Conclusion: Stereotactic body radiotherapy is an effective and safe method of providing local control of oligometastatic liver metastases in colorectal cancer as part of a combined treatment approach. Further studies are required to individualize the indications for this treatment method.ΠΠ±ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠ΅: ΠΡΠΎΠ±Π»Π΅ΠΌΠ° Π»Π΅ΡΠ΅Π½ΠΈΡ Π±ΠΎΠ»ΡΠ½ΡΡ
Ρ Π½Π΅ΡΠ΅Π·Π΅ΠΊΡΠ°Π±Π΅Π»ΡΠ½ΡΠΌΠΈ ΠΌΠ΅ΡΠ°ΡΡΠ°Π·Π°ΠΌΠΈ ΡΠ°ΠΊΠ° ΡΠΎΠ»ΡΡΠΎΠΉ ΠΊΠΈΡΠΊΠΈ Π² ΠΏΠ΅ΡΠ΅Π½ΠΈ Π² Π½Π°ΡΡΠΎΡΡΠ΅Π΅ Π²ΡΠ΅ΠΌΡ Π΄Π°Π»Π΅ΠΊΠ° ΠΎΡ ΡΠ΅ΡΠ΅Π½ΠΈΡ. ΠΠ΄ΠΈΠ½ ΠΈΠ· Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΡΡ
ΠΏΠΎΠ΄Ρ
ΠΎΠ΄ΠΎΠ² β ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΡΡΠ΅ΡΠ΅ΠΎΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π»ΡΡΠ΅Π²ΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ.Π¦Π΅Π»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ: ΠΡΠ΅Π½ΠΊΠ° Π½Π΅ΠΏΠΎΡΡΠ΅Π΄ΡΡΠ²Π΅Π½Π½ΡΡ
ΠΈ ΠΎΡΠ΄Π°Π»Π΅Π½Π½ΡΡ
ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΎΠ² ΡΡΠ΅ΡΠ΅ΠΎΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π»ΡΡΠ΅Π²ΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ Π² ΡΠ°ΠΌΠΊΠ°Ρ
ΠΊΠΎΠΌΠ±ΠΈΠ½ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ Π»Π΅ΡΠ΅Π½ΠΈΡ ΡΠ°ΠΊΠ° ΡΠΎΠ»ΡΡΠΎΠΉ ΠΊΠΈΡΠΊΠΈ Ρ ΠΎΠ»ΠΈΠ³ΠΎΠΌΠ΅ΡΠ°ΡΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΠΎΡΠ°ΠΆΠ΅Π½ΠΈΠ΅ΠΌ ΠΏΠ΅ΡΠ΅Π½ΠΈ.ΠΠ΅ΡΠΎΠ΄Ρ: ΠΠ°Π½Π½ΠΎΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΠΊΠ°ΠΊ ΡΠ΅ΡΡΠΎΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ΅ ΠΎΡΠΊΡΡΡΠΎΠ΅ ΠΊΠΎΠ½ΡΡΠΎΠ»ΠΈΡΡΠ΅ΠΌΠΎΠ΅ Π½Π΅ΡΠ°Π½Π΄ΠΎΠΌΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ΅ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅. ΠΠ΄Π½ΠΎΠ³ΠΎΠ΄ΠΈΡΠ½ΡΠΉ Π»ΠΎΠΊΠ°Π»ΡΠ½ΡΠΉ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ, ΠΎΠ΄Π½ΠΎΠ³ΠΎΠ΄ΠΈΡΠ½Π°Ρ ΠΎΠ±ΡΠ°Ρ Π²ΡΠΆΠΈΠ²Π°Π΅ΠΌΠΎΡΡΡ, Π²ΡΠΆΠΈΠ²Π°Π΅ΠΌΠΎΡΡΡ Π±Π΅Π· ΠΏΡΠΎΠ³ΡΠ΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΡΠΎΠΊΡΠΈΡΠ½ΠΎΡΡΡ Π±ΡΠ»ΠΈ ΠΎΡΠ΅Π½Π΅Π½Ρ Ρ 60 Π±ΠΎΠ»ΡΠ½ΡΡ
Ρ ΠΎΠ»ΠΈΠ³ΠΎΠΌΠ΅ΡΠ°ΡΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΠΎΡΠ°ΠΆΠ΅Π½ΠΈΠ΅ΠΌ ΠΏΠ΅ΡΠ΅Π½ΠΈ Π½Π° ΡΠΎΠ½Π΅ ΠΊΠΎΠ»ΠΎΡΠ΅ΠΊΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΠΊΠ°, ΠΊΠΎΡΠΎΡΡΠΌ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»Π°ΡΡ ΡΡΠ΅ΡΠ΅ΠΎΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠ°Ρ Π»ΡΡΠ΅Π²Π°Ρ ΡΠ΅ΡΠ°ΠΏΠΈΡ, ΠΌΠ΅Π΄ΠΈΠ°Π½Π° ΡΡΠΌΠΌΠ°ΡΠ½ΠΎΠΉ ΠΎΡΠ°Π³ΠΎΠ²ΠΎΠΉ Π΄ΠΎΠ·Ρ 54 ΠΡ.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ: ΠΠ΅Π΄ΠΈΠ°Π½Π° Π½Π°Π±Π»ΡΠ΄Π΅Π½ΠΈΡ ΡΠΎΡΡΠ°Π²ΠΈΠ»Π° 20,1 ΠΌΠ΅Ρ. ΠΠ΄Π½ΠΎΠ³ΠΎΠ΄ΠΈΡΠ½ΡΠΉ Π»ΠΎΠΊΠ°Π»ΡΠ½ΡΠΉ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ (ΠΠ) Π΄ΠΎΡΡΠΈΠ³ 73,7 % (95 %ΠΠ = 62,7β86,6 %). ΠΠ΄Π½ΠΎΠ³ΠΎΠ΄ΠΈΡΠ½Π°Ρ ΠΎΠ±ΡΠ°Ρ Π²ΡΠΆΠΈΠ²Π°Π΅ΠΌΠΎΡΡΡ (ΠΠ) ΡΠΎΡΡΠ°Π²ΠΈΠ»Π° 92,8 % (95 % ΠΠ = 86,3β99,9 %), ΠΎΠ΄Π½ΠΎΠ³ΠΎΠ΄ΠΈΡΠ½Π°Ρ Π²ΡΠΆΠΈΠ²Π°Π΅ΠΌΠΎΡΡΡ Π±Π΅Π· ΠΏΡΠΎΠ³ΡΠ΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ (ΠΠΠ) β 31,3 % (95 %ΠΠ = 21,1β46,4 %) Ρ ΠΌΠ΅Π΄ΠΈΠ°Π½ΠΎΠΉ 8,1 ΠΌΠ΅Ρ. Π’ΠΎΠΊΡΠΈΡΠ½ΠΎΡΡΠΈ 3 ΡΡΠ΅ΠΏΠ΅Π½ΠΈ ΠΈ Π²ΡΡΠ΅ Π½Π΅ ΠΎΡΠΌΠ΅ΡΠ΅Π½ΠΎ. Π‘Π»ΡΡΠ°Π΅Π² ΡΠ°Π΄ΠΈΠ°ΡΠΈΠΎΠ½Π½ΠΎ ΠΈΠ½Π΄ΡΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΠΏΠ΅ΡΠ΅Π½ΠΎΡΠ½ΠΎΠΉ Π½Π΅Π΄ΠΎΡΡΠ°ΡΠΎΡΠ½ΠΎΡΡΠΈ Π½Π΅ Π½Π°Π±Π»ΡΠ΄Π°Π»ΠΎΡΡ. ΠΡΠ»ΠΎ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ Π΄ΠΎΠ·Π° ΠΎΠ±Π»ΡΡΠ΅Π½ΠΈΡ (HR = 0,88, 95 % ΠΠ = 0,81β0,95, p = 0,00087), ΡΠ°Π·ΠΌΠ΅Ρ ΠΌΠ΅ΡΠ°ΡΡΠ°Π·ΠΎΠ² (HR = 1,51, 95 % ΠΠ = 1,07β2,12, Ρ = 0,01858) ΠΈ ΠΈΡ
ΡΠΈΡΠ»ΠΎ (HR = 1,8 95 % ΠΠ = 1,01β3,22, Ρ = 0,04669) ΡΠ²Π»ΡΡΡΡΡ Π·Π½Π°ΡΠΈΠΌΡΠΌΠΈ ΡΠ°ΠΊΡΠΎΡΠ°ΠΌΠΈ ΡΠΈΡΠΊΠ° Π΄Π»Ρ ΠΠ. Π Π°Π·ΠΌΠ΅Ρ ΠΌΠ΅ΡΠ°ΡΡΠ°Π·ΠΎΠ² > 3 ΡΠΌ ΡΠ²Π»ΡΠ΅ΡΡΡ Π·Π½Π°ΡΠΈΠΌΡΠΌ ΡΠ°ΠΊΡΠΎΡΠΎΠΌ ΡΠΈΡΠΊΠ° ΠΏΠΎ ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΡ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Ρ Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ (HR = 5.5, 95 % ΠΠ = 1.7β17.9, p = 0.005) ΠΈ ΠΠ (HR = 3.8, 95 % ΠΠ = 1.3β11.7, p = 0.02).ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅: Π‘ΡΠ΅ΡΠ΅ΠΎΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠ°Ρ Π»ΡΡΠ΅Π²Π°Ρ ΡΠ΅ΡΠ°ΠΏΠΈΡ β ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΠΉ ΠΈ Π±Π΅Π·ΠΎΠΏΠ°ΡΠ½ΡΠΉ ΠΌΠ΅ΡΠΎΠ΄ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠ΅Π½ΠΈΡ Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ Π½Π°Π΄ ΠΎΠ»ΠΈΠ³ΠΎΠΌΠ΅ΡΠ°ΡΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΠΎΡΠ°ΠΆΠ΅Π½ΠΈΠ΅ΠΌ ΠΏΠ΅ΡΠ΅Π½ΠΈ ΠΏΡΠΈ ΠΊΠΎΠ»ΠΎΡΠ΅ΠΊΡΠ°Π»ΡΠ½ΠΎΠΌ ΡΠ°ΠΊΠ΅ Π² ΡΠ°ΠΌΠΊΠ°Ρ
ΠΊΠΎΠΌΠ±ΠΈΠ½ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠΎΠ΄Ρ
ΠΎΠ΄Π° ΠΊ Π»Π΅ΡΠ΅Π½ΠΈΡ. Π’ΡΠ΅Π±ΡΠ΅ΡΡΡ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΠ΅ Π΄Π°Π»ΡΠ½Π΅ΠΉΡΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π΄Π»Ρ ΠΈΠ½Π΄ΠΈΠ²ΠΈΠ΄ΡΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΈΠΉ ΠΊ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Π° Π»Π΅ΡΠ΅Π½ΠΈΡ ΠΈ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ Π΅Π³ΠΎ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΠΈ.
Attempt to produce element 120 in the 244 Pu + 58 Fe reaction
An experiment aimed at the synthesis of isotopes of element 120 has been performed using the 244 Pu( 58 Fe,xn) 302βx 120 reaction. No decay chains consistent with fusion-evaporation reaction products were observed during an irradiation with a beam dose of 7.1 Γ 10 18 330-MeV 58 Fe projectiles. The sensitivity of the experiment corresponds to a cross section of 0.4 pb for the detection of one decay
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