Nuclear Experiment·nucl-ex

Tue·Jun 9, 2015Tuesday·June 9, 2015

11 papers—5 primary·6 cross-listed·reconstructed*

01*
Complex signal amplitude analysis for complete fusion nuclear reaction products
Yu.S.Tsyganov🇷🇺
A complex analysis has been performed on the energy amplitude signals corresponding to events of Z=117 element measured in the 249Bk+48Ca complete fusion nuclear reaction. These signals were detected with PIPS position sensitive detector. The significant values of pulse height defect both for recoils (ER) and fission fragments (FF) were measured. Comparison with the computer simulations and empirical formulae has been performed both for ER and FF signals.
nucl-ex0 citations
02*
Basic non-linear effects in silicon radiation detector in detection of highly ionizing particles: registration of ultra rare events of superheavy nuclei in the long-term experiments
Y. S. Tsyganov🇷🇺
Sources of non-linear response of PIPS detector, when detecting highly ionizing particles like recoils (EVR), fission fragments and heavy ions, including formation of large pulse-height defect (PHD) are considered. An analytical formula to calculate the recombination component of EVR PHD is proposed on the base of surface recombination model with some empirical correction. PC-based simulation code for generating the spectrum of the measured recoil signal amplitudes of the heavy implanted nuclei is presented. The simulated spectra are compared with the experimental ones for the different facilities: the Dubna Gas Filled Recoil Separator (DGFRS), SHIP and RIKEN gas-filled separator. After the short reviewing of the detection system of the DGFRS, is considered the real-time matrix algorithm application aimed to the radical background suppression in the complete-fusion heavy-ion induced nuclear reactions. Typical examples of application in the long term experiments aimed to the synthesis of superheavy elements Z=112-118 are presented [1-9].
nucl-ex0 citations
03*
Physical basis of critical analysis
Y. S. Tsyganov🇷🇺
A new approach to provide a fruitful analysis of signal amplitude is proposed. It is this method that has made it possible to eliminate some observed artificial events from the list of candidates for decays of superheavy nuclei. Examples of estimates of measured amplitudes of evaporation residues (EVR) are presented. Some attention is paid to a new hard statistical criterion for detecting rare events. This criterion can be applied in the case of significant role of random factors.
nucl-ex1 citation
04*
Experimental study of $η$ meson photoproduction reaction at MAMI
V. L. Kashevarov · the A2 Collaboration at MAMI
New data for the differential cross sections, polarization observables $T$ , $F$ , and $E$ in the reaction of $η$ photoproduction on proton from the threshold up to a center-of-mass energy of W=1.9 GeV are presented. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The polarization measurements were made using a frozen-spin butanol target and circularly polarized photon beam. The results are compared to existing experimental data and different PWA predictions. The data solve a long-standing problem related the angular dependence of older $T$ data close to threshold. The unexpected relative phase motion between $s$ - and $d$ -wave amplitudes required by the old data is not confirmed. At higher energies, all model predictions fail to reproduce the new polarization data indicating a significant impact on our understanding of the underlying dynamics of $η$ meson photoproduction. Furthermore, we present a fit of the new data and existing data from GRAAL for $Σ$ asymmetry based on an expansion in terms of associated Legendre polynomials. A Legendre decomposition shows the sensitivity to small partial-wave contributions. The sensitivity of the Legendre coefficients to the nucleon resonance parameters is shown using the $η$ MAID isobar model.
nucl-exhep-exEPJ Web Conf.(2015)·4 citations
05*
Methods for a quantitative evaluation of odd-even staggering effects
Alessandro Olmi🇮🇹 · Silvia Piantelli🇮🇹
Odd-even effects, also known as "staggering" effects, are a common feature observed in the yield distributions of fragments produced in different types of nuclear reactions. We review old methods, and we propose new ones, for a quantitative estimation of these effects as a function of proton or neutron number of the reaction products. All methods are compared on the basis of Monte Carlo simulations. We find that some are not well suited for the task, the most reliable ones being those based either on a non-linear fit with a properly oscillating function or on a third (or fourth) finite difference approach. In any case, high statistic is of paramount importance to avoid that spurious structures appear just because of statistical fluctuations in the data and of strong correlations among the yields of neighboring fragments.
nucl-exEPJA(2015)·7 citations
06*
Method of active correlations in the experiment 249Cf+48Ca->297118 +3n
Yu.S.Tsyganov🇷🇺 · A.M.Sukhov · A.N.Polyakov
Two decay chains originated from the even-even isotope 294118 produced in the 3n-evaporation channel of the 249Cf+48Ca reaction. Method of active correlations is applied to suppress backgrounds associated with the cyclotron. It is planned to apply this technique for the forthcoming experiment aimed to the synthesis of Z=120 element. A calibration dependence for a recoil measured energy signal is presented as well as a computer simulation spectrum for Z=118 nuclei.
↳ physics.ins-detnucl-ex0 citations
07*
A multi-interval MBSC theory for active correlations technique
Yu.S.Tsyganov🇷🇺
The purpose of the paper is the development of the formalism for the treatment of rare events especially, when one applies active correlation method to suppress background products in the heavy ion induced complete fusion nuclear reactions. This formalism in fact is an extension of classical background signal combinations formalism for the case of time multi intervals.
↳ physics.ins-detnucl-ex0 citations
08*
Active Correlation Technique: Status and Development
Yury Tsyganov🇷🇺
During the recent years, at the FLNR a successful cycle of experiments has been accomplished on the synthesis of the superheavy elements with Z=112 to Z=118 using 48Ca ion beam. From the viewpoint of the detection of rare decays and background suppression, this success was achieved due to the application of a new radical technique, the method of active correlations. The method employs search in a real time mode for a pointer to a probable correlation like recoil alpha for switching the beam off. In the case of detection in the same detector strip an additional alpha decay event, of beam OFF time interval is prolonged automatically
↳ physics.ins-detnucl-ex0 citations
09*
New Detection System for Heavy Element Research
Y. S. Tsyganov🇷🇺 · A. N. Polyakov · A. A. Voinov🇺🇸 · M. V. Shumeyko
New detection system design for heavy element research with 48Ca projectile has been reported. This system is based on application of 32 position sensitive strip PIPS detector and low pressure pentane filled TOF detector application in 48Ca induced nuclear reactions. To suppress beam associated background products new version of real time method of active correlations has been applied. Examples of applications in 249Bk+48Ca and 243Am+48Ca reactions are presented. The system development to operate together with the digital ORNL detection system to provide a quick search for recoil to alpha correlation chains has been discussed too.
↳ physics.ins-detnucl-ex0 citations
10*
4 $π$ detector for study of Zeno effect using 220Rn -> 216Po alpha->alpha correlated chains
L. Nadderd · Y. S. Tsyganov🇷🇺 · K. Subotic · A. N. Polyakov · Y. V. Lobanov · A. V. Rykhlyuk
First test of the 4pi detector for study of exponential law of radioactive decay and possibility of observation of Zeno effect [1-3], measuring the mean life of 216Po is presented. This detector consists of two surface-barrier n-Si(Au) detectors placed in the close contact ( <1mm) to each other. Th foil is used as a generator of Rn- gas. The foil was covered by nuclear filter with 0.4 mm pores and placed in the bottom of vacuum chamber. So, direct alpha-particles can not reach the detector active surface. The measured half-live of 216Po of 143.5 (0.6) ms is in agreement with literature sources. It is shown, that for the definite source the random background correlation counts are mostly caused by the 220Rn - 216Po alpha activities and that it is not an easy task to decrease a background level of units of percents in the time region >4T1/2. Both, the data acquisition system and the vacuum chamber design are presented in brief.
↳ physics.ins-detnucl-ex0 citations
11*
Uncertainty analysis and order-by-order optimization of chiral nuclear interactions
B. D. Carlsson🇸🇪 · A. Ekström🇺🇸 · C. Forssén🇸🇪 · D. Fahlin Strömberg🇸🇪 · G. R. Jansen🇺🇸 · O. Lilja🇸🇪 · M. Lindby🇸🇪 · B. A. Mattsson🇸🇪 · K. A. Wendt🇺🇸
Chiral effective field theory (chiEFT) provides a systematic approach to describe low-energy nuclear forces. Moreover, chiEFT is able to provide well-founded estimates of statistical and systematic uncertainties -- although this unique advantage has not yet been fully exploited. We fill this gap by performing an optimization and statistical analysis of all the low-energy constants (LECs) up to next-to-next-to-leading order. Our optimization protocol corresponds to a simultaneous fit to scattering and bound-state observables in the pion-nucleon, nucleon-nucleon, and few-nucleon sectors, thereby utilizing the full model capabilities of chiEFT. We study the effect on other observables by demonstrating error-propagation methods that can easily be adopted by future works. We employ mathematical optimization and implement automatic differentiation to attain efficient and machine-precise first- and second-order derivatives of the objective function with respect to the LECs. We use power-counting arguments to estimate the systematic uncertainty that is inherent to chiEFT and we construct chiral interactions at different orders with quantified uncertainties. Statistical error propagation is compared with Monte Carlo sampling showing that statistical errors are in general small compared to systematic ones. In conclusion, we find that a simultaneous fit to different sets of data is critical to (i) identify the optimal set of LECs, (ii) capture all relevant correlations, (iii) reduce the statistical uncertainty, and (iv) attain order-by-order convergence in chiEFT. Furthermore, certain systematic uncertainties in the few-nucleon sector are shown to get substantially magnified in the many-body sector; in particlar when varying the cutoff in the chiral potentials. The methodology and results presented in this Paper open a new frontier for uncertainty quantification in ab initio nuclear theory.
↳ nucl-thnucl-exphysics.comp-phPRX(2016)·213 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.