Search

The kinetic characteristics of the process of synthesis of Ni nanopowder (NP) by the chemical metallurgy method are studied. Nickel NP is obtained by reduction of NiO nanopowder with hydrogen in a tubular furnace at temperatures in the range from 240 to 280°C. Nickel oxide nanopowder is prepared by thermal decomposition of nickel hydroxide Ni(OH)2 at 300°C, which has been synthesized in advance by chemical precipitation from aqueous solutions of nickel nitrate 10 wt % and alkali NaOH 10 wt % with pH 9 at room temperature. It is found that NiO NP is more readily reduced at temperatures above 250°C. The rate constant of the reduction process at 280°C is about 2.5 times higher than in the case of reduction at 240°C. The duration of the reduction process at 280°C is shorter by a factor of more than two in comparison with the case of reduction at 240°C. Based on the results of calculation of the activation energy of the reduction process from isothermal data, an assumption is made about the kinetically controlled rate-limiting regime of the reduction of NiO NP. It is revealed that Ni nanoparticles obtained by hydrogen reduction of nickel oxide have an average size in the range of 60–120 nm, and each of them is connected to several adjacent particles by necks.

The ^{13}C(α,n)^{16}O reaction is the main neutron source for the slow-neutron-capture process in asymptotic giant branch stars and for the intermediate process. Direct measurements at astrophysical energies in above-ground laboratories are hindered by the extremely small cross sections and vast cosmic-ray-induced background. We performed the first consistent direct measurement in the range of E_{c.m.}=0.24 to 1.9 MeV using the accelerators at the China Jinping Underground Laboratory and Sichuan University. Our measurement covers almost the entire intermediate process Gamow window in which the large uncertainty of the previous experiments has been reduced from 60% down to 15%, eliminates the large systematic uncertainty in the extrapolation arising from the inconsistency of existing datasets, and provides a more reliable reaction rate for the studies of the slow-neutron-capture and intermediate processes along with the first direct determination of the alpha strength for the near-threshold state.

With the recent advances in tumor treatments,the prognosis of patients with malignancies have been greatly improved.The strategy of surgical treatments for spinal metastases has drawn wide attention.Compared with traditional open surgery,minimally invasive spine surgery (MISS) results in similar outcomes,less trauma and more rapid recovery.For patients with spinal metastases,shorter recovery time permits earlier postoperative radiotherapy,achieving better tumor control.This paper discussed the application of MISS in the treatments of spinal metastases in terms of the concept,surgical purpose,indications and surgical options of MISS,hoping to provide reference for clinical practice.随着诊疗水平的提高，恶性肿瘤患者的生存质量及预后大大改善，脊柱转移性肿瘤患者的手术治疗策略受到广泛关注。微创脊柱手术（MISS）与传统开放手术相比，治疗效果相似，创伤更小，康复时间更短。对于脊柱转移性肿瘤患者，更短的康复时间有助于早期开展术后放疗，从而达到更满意的肿瘤控制效果。本文从MISS的概念、手术目的、适应证、术式选择等方面对其在脊柱转移性肿瘤治疗中的应用进行探讨，以为临床实践提供参考。.

The 12C+12C fusion reaction was studied in the range of E c.m.=8.9 to 21 MeV using the active-target Time Projection Chamber. With full information on all tracks of the reaction products, cross sections of the 12C(12C,8Be)16Og.s. channel and the 12C(12C,3α)12C channel could be measured down to the level of a few milibarns. The 12C(12C,8Be)16Og.s. reaction channel was determined to be 10 mb at E c.m.=11.1 MeV, supporting the direct α transfer reaction mechanism. The 12C(12C,3α)12C reaction channel was studied for the first time using an exclusive measurement. Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al. [Phys. Rev. C 21, 579 (1980)]. Our comparisons with statistical model calculations suggest that the 3α channel is dominated by the fusion evaporation process at E c.m. > 19 MeV. The additional contribution of the 3α channel increases the fusion reaction cross section by 10% at energies above 20 MeV. We also find that an additional reaction mechanism is needed to explain the measured cross section at E c.m. < 15 MeV at which point the statistical model prediction vanishes.

Fluorine is one of the most interesting elements in nuclear astrophysics, where the ^{19}F(p,α)^{16}O reaction is of crucial importance for Galactic ^{19}F abundances and CNO cycle loss in first generation Population III stars. As a day-one campaign at the Jinping Underground Nuclear Astrophysics experimental facility, we report direct measurements of the essential ^{19}F(p,αγ)^{16}O reaction channel. The γ-ray yields were measured over E_{c.m.}=72.4-344 keV, covering the Gamow window; our energy of 72.4 keV is unprecedentedly low, reported here for the first time. The experiment was performed under the extremely low cosmic-ray-induced background environment of the China JinPing Underground Laboratory, one of the deepest underground laboratories in the world. The present low-energy S factors deviate significantly from previous theoretical predictions, and the uncertainties are significantly reduced. The thermonuclear ^{19}F(p,αγ)^{16}O reaction rate has been determined directly at the relevant astrophysical energies.

The ^{12}C(α,γ)^{16}O reaction is one of the most crucial reactions in nuclear astrophysics. The E2 external capture to the ^{16}O ground state (GS) has not been emphasized in previous analyses but may make a significant contribution to the ^{12}C(α,γ)^{16}O cross section depending on the value of the GS asymptotic normalization coefficient (ANC). In the present work, we determine this ANC to be 337±45 fm^{-1/2} through the ^{12}C(^{11}B,^{7}Li)^{16}O reaction using a high-precision magnetic spectrograph. This sheds light on the existing large discrepancy of more than 2 orders of magnitude between the previously reported ANC values. Based on the new ANC, we experimentally constrain the GS external capture and show that through interference with the high energy tail of the 2^{+} subthreshold state, a substantial enhancement in the GS S_{E2}(300) factor can be obtained (70±7 keV b) compared to that of a recent review (45 keV b), resulting in an increase of the total S factor from 140 to 162 keV b, which is now in good agreement with the value obtained by reproducing supernova nucleosynthesis calculations with the solar-system abundances. This work emphasizes that the external capture contribution for the ground state transition cannot be neglected in future analyses of the ^{12}C(α,γ)^{16}O reaction.

失眠与阻塞性睡眠呼吸暂停是两种最常见的睡眠障碍，二者常常合并存在，增加患者社会功能受损及躯体疾病患病风险，增加临床治疗难度。因此，在临床诊疗方面，应注重两者共病的筛查，对共病者制定个体化的治疗策略以提高临床疗效。.

We performed indirect measurements of the neutron-induced reactions \(^{7}\)Be(n,p)\(^{7}\)Li and \(^{7}\)Be(n,\(\mathsf \alpha \))\(^{4}\)He simultaneously by the Trojan Horse method relevant to the cosmological \(^7\)Li problem. Preliminary excitation functions for \((n,p_0)\) and \((n,\alpha )\) are basically consistent with the previous studies, and new information about the \((n,p_1)\) contribution suggests possible enhancement of the total reaction rate.

Flat bottom self-pierce riveting is a novel metal sheet joining process because it does not need mold design of self-pierce riveting. Joints have flat bottom and high strength, so that flat bottom self-pierce riveting has wide development prospects. With the help of the DEFORM-2D software, this paper studied the effects of friction factors between AZ31 magnesium alloy sheets were studied, and then special simulations were carried out to investigate their effects on joints. The analysis indicates that the appropriate friction factor among blank holder, rivet, sheets and bottom plate is 0.1–0.5 and the friction factors have obvious effects on the quality of joints. The final results may provide the further research with essential guidance.

Reaccelerated radioactive beams near the Coulomb barrier, which are starting to be available from the ReA3 accelerator at NSCL and in next future at FRIB, will open up new opportunities for the study of nuclear structure near the drip lines. Efficient measurement techniques must be developed to compensate for the limited intensity of the most exotic beams. The Active-Target Time Projection Chamber (AT-TPC) constructed at MSU solves this problem by providing the increased luminosity of a thick target while maintaining a good energy resolution by tracking the reaction vertex over an essentially 4 π solid angle. The AT-TPC and similar detectors allow us to take full advantage of the radioactive ion beams at present and future nuclear physics facilities to explore the frontier of rare isotopes.

Heavy ion fusion reactions play important roles in a wide variety of stellar burning scenarios. 12C+12C, 12C+16O and 16O+16O are the principle reactions during the advance burning stages of massive star. 12C+12C also triggers the happening of superburst and Type Ia supernovae. The heavy ion fusion reactions of the neutron-rich isotopes such as 24O are the major heating source in the crust of neutron star. In this talk, I will review the challenges and the recent progress in the study of these heavy ion fusion reactions at stellar energies. The outlook for the studies of the astrophysical heavy-ion fusion reactions will also be presented.

The study of the $^{17}\mathrm{O}(n,\ensuremath{\alpha})^{14}\mathrm{C}$ reaction has been performed by means of the Trojan horse method (THM) applied to the quasifree $^{2}\mathrm{H}(^{17}\mathrm{O},\ensuremath{\alpha}^{14}\mathrm{C})^{1}\mathrm{H}$ reaction induced at a beam energy of 43.5 MeV. The THM allowed us to study the 8121-keV $^{18}\mathrm{O}^{*}$ resonant level, for which the previous THM investigation pointed out the ability of the method to overcome the centrifugal barrier suppression effects in the entrance channel. Here, in view of the developments of the method for resonant reactions, the detailed analysis of the performed experiment will be discussed, focusing on the extraction of the 8121-keV resonance strength for which no information is present in scientific literature. Moreover, the experimental results clearly show the excitation of the subthreshold level centered at $\ensuremath{-}6$ keV in the center-of-mass system, which is fundamental to determine the $^{17}\mathrm{O}(n,\ensuremath{\alpha})^{14}\mathrm{C}$ reaction rate of astrophysical interest. Finally, a new recommended reaction rate is presented for future astrophysical application.

Ni doped ZnO nanoparticles were synthesized by a solution route and annealed in O2, air, and Ar, respectively. X-ray diffraction and X-ray photoelectron spectroscopy measurements show that the samples possess typical wurtzite structure and have no other impurity phases. Magnetization loops for ZnO samples were measured and clearly show typical ferromagnetic saturation behavior. With the defect analysis based on photoluminescence spectroscopy, the effect of defects on the nature and origin of ferromagnetism was investigated. The results suggest that oxygen vacancies, especially single ionized oxygen vacancies, play a crucial role in mediating ferromagnetism in the Ni doped ZnO.

The extinct p-process nuclide 146Sm (t1/2 = 103 ± 5 Myr) is known to have been present in the Early-Solar System and has been proposed as an astrophysical chronometer. 146Sm is also intensely used to date meteorite and planetary differentiation processes, enhancing the importance of an accurate knowledge of the 146Sm half-life. We are engaged in a new determination of the 146Sm half-life in which the 146Sm/147Sm atom ratio is determined by accelerator mass spectrometry at the ATLAS facility of Argonne National Laboratory. In order to reduce systematic errors in the AMS determination of the 146Sm/147Sm ratios (in the range of 10-7-10-9), 146Sm and 147Sm ions were alternately counted in the same detector in the focal plane of a gas-filled magnet, respectively in continuous-wave and attenuated mode. Quantitative attenuation is obtained with the 12 MHz pulsed and ns-bunched ATLAS beam by chopping beam pulses with an RF sweeper in a ratio (digitally determined) down to 1:106. The experiments and preliminary results are discussed. © 2012 Elsevier B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

To evaluate the diagnosis value of photoplethysmography (PPG)-based device for detecting obstructive sleep apnea syndrome.Patients who visited sleep medicine center in West China hospital from March 2014 to March 2015 with a main complain of snoring were selected into this study, and they were simultaneously monitored with the PPG-based device while undergoing polysomnography (PSG). Using PSG as"gold standard", the sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) as well as corresponding areas under the receiver operator curves for an apnea hypopnea index (AHI) ≥5/h, ≥15/h and ≥30/h were calculated for PPG.Valid results were available for 93 subjects, among them there were 64 men and 29 women with a mean age of (44±13) years old.There were no significant difference between total sleep time, wake time after sleep onset, AHI and oxygen saturation derived by PPG and PSG.Positive correlation was found between PPG-derived and PSG-derived AHI (r=0.945). For AHI≥5/h, ≥15/h and ≥30/h respectively according PSG, sensitivity was 93%, 88%, 92%, specificity was 79%, 93%, 95%, PPV was 95%, 97%, 96%, NPV 75%, 76%, 91% for PPG. The corresponding areas under the receiver operator characteristic curves were 0.981, 0.996 and 0.995 respectively.PPG-derived data is consistent with simultaneous in-lab PSG in the diagnosis of obstructive sleep apnea syndrome.

The Prototype AT-TPC, a detector based on time projection chamber (TPC) technology was built at the National Superconducting Cyclotron Laboratory, Michigan State University. The chamber gas, called the active target, of the Prototype AT-TPC is utilized simultaneously as a reaction target and a tracking medium of charged particles for measuring low-energy nuclear reactions. In pursuit of luminosity, efficiency and resolution for reaction studies at a new generation of radioactive isotope facilities, the Prototype AT-TPC provides one of the largest active volumes in the world measuring 25 cm in diameter and 50 cm long along the beam axis, millimeter-precision tracking capability, and a high electric field of 1 kV/cm/atm for fast electron drift, which limits the detector dead time. Commissioning of the detector using standard alpha sources and radioactive 6 He beams has demonstrated the detector's long-term stability as well as its performance, which allowed good reconstruction of reaction kinematics.

A particle- γ coincidence technique has been used to measure the fusion cross-section in the system 12C+12C at low beam energies. Based on these results, it should be possible to measure this important fusion cross-section down to the 10 pb level within a week-long run.

Proton radioactivity from 117 La was re-investigated with much improved statistics and precision. Only the ground-state proton decay ( E p = 813 ( 3 ) keV , T 1 / 2 = 20.1 ( 25 ) ms ) was observed, no evidence for a previously reported isomeric proton decay was found. Prompt γ rays in 117 La were identified using the Recoil–Decay Tagging method. Overall the data indicate that the proton-emitting state is associated with a K π = 3 / 2 + configuration, in agreement with all the published proton-decay calculations and predictions for the ground-state configuration of 117 La calculated in the framework of either adiabatic or non-adiabatic particle models. However, this is not in agreement with the most recent state-of-the-art quasi-particle non-adiabatic model calculations which predict a K π = 7 / 2 − configuration.

Nanocrystalline supersaturated solid solutions were formed by mechanically alloyed Fe-28Al (in atom percent) from the elemental powder of iron and aluminum. Phase evolution, grain size and lattice strain of these powders were determined and discussed. A thermodynamic model was developed based on semi-experimental theory of Miedema to calculate the chemical driving force for phase evolution. The influence of thermodynamic driving forces, namely the Gibbs free energy of mixing, for the solid solution and the amorphous was discussed and corresponded to the sequence of phase formations during mechanical alloying.

Nanocrystalline supersaturated solid solutions were formed by mechanically alloyed Fe-28Al (in atom percent) from the elemental powder of iron and aluminum. Phase evolution, grain size and lattice strain of these powders were determined and discussed. A thermodynamic model was developed based on semi-experimental theory of Miedema to calculate the chemical driving force for phase evolution. The influence of thermodynamic driving forces, namely the Gibbs free energy of mixing, for the solid solution and the amorphous was discussed and corresponded to the sequence of phase formations during mechanical alloying.

Transition-metal-(Cr, Mn, and Ni)-doped zinc oxide (ZnO) with the concentration of 2.5% and pure ZnO nanocrystalline (nc) films have been fabricated on quartz substrates by the sol−gel method. The X-ray diffraction analysis shows that the films are polycrystalline with the wurtzite phase. The E2high phonon mode shifts about 7 cm−1 with different transition metals, and the A1(LO) phonon mode redshifts 4 cm−1 with the ionic radius of doping elements. From the transmittance spectra, all films are highly transparent in the visible region and exhibit Urbach tail states in the ultraviolet range because of the crystalline defects and grain boundaries. The optical band gap of the films decreases with increasing the orbital occupation numbers of 3d electrons due to the orbital splitting of magnetic ions. It was found that a distinct and strong excitonic transition appears beyond the fundamental absorption region at room temperature. Ultraviolet and near-infrared electronic transitions can be observed and show the ...

The clustering of $\ensuremath{\alpha}$ particles in atomic nuclei results in the self-organization of various geometrical arrangements at the femtometer scale. The one-dimensional alignment of multiple $\ensuremath{\alpha}$ particles is known as linear-chain structure, evidence of which has been highly elusive. We show via resonant elastic and inelastic $\ensuremath{\alpha}$ scattering of a radioactive $^{10}\mathrm{Be}$ beam that excited states in the neutron-rich nucleus $^{14}\mathrm{C}$ agree with recent predictions of linear-chain structure based on an antisymmetrized molecular dynamics model.

The $^{17}\text{O}(p,\ensuremath{\alpha})^{14}\text{N}$ and $^{17}\text{O}(p,\ensuremath{\gamma})^{18}\text{F}$ reactions are of paramount importance for the nucleosynthesis in a number of stellar sites, including red giants (RGs), asymptotic giant branch (AGB) stars, massive stars, and classical novae. In particular, they govern the destruction of $^{17}\text{O}$ and the formation of the short-lived radioisotope $^{18}\text{F}$, which is of special interest for $\ensuremath{\gamma}$-ray astronomy. At temperatures typical of the above-mentioned astrophysical scenario, $T=0.01$--0.1 GK for RG, AGB, and massive stars and $T=0.1$--0.4 GK for a classical nova explosion, the $^{17}\text{O}(p,\ensuremath{\alpha})^{14}\text{N}$ reaction cross section is dominated by two resonances: one at about ${E}_{R}^{cm}=65$ keV above the $^{18}\text{F}$ proton threshold energy, corresponding to the ${E}_{X}=5.673$ MeV level in $^{18}\text{F}$, and another one at ${E}_{R}^{cm}=183$ keV $({E}_{X}=5.786$ MeV). We report on the indirect study of the $^{17}\text{O}(p,\ensuremath{\alpha})^{14}\text{N}$ reaction via the Trojan Horse method by applying the approach recently developed for extracting the strength of narrow resonance at ultralow energies. The mean value of the strengths obtained in the two measurements was calculated and compared with the direct data available in literature. This value was used as input parameter for reaction-rate determination and its comparison with the result of the direct measurement is also discussed in the light of the electron screening effect.

The proton decay of $^{53}\mathrm{Co}^{m}$($3174.1\phantom{\rule{4.pt}{0ex}}\text{keV},19/{2}^{\ensuremath{-}}$) was investigated via the fragmentation of a $^{58}\mathrm{Ni}$ primary beam. The proton-decay energy was determined with an improved precision to be $1558\phantom{\rule{0.16em}{0ex}}(8)\phantom{\rule{4.pt}{0ex}}\text{keV}$. With this new result and the mass of $^{53}\mathrm{Co}^{m}$, the $^{52}\mathrm{Fe}$ mass excess was derived to be $\ensuremath{-}48\phantom{\rule{0.16em}{0ex}}330\phantom{\rule{0.16em}{0ex}}(8)\phantom{\rule{4.pt}{0ex}}\text{keV}$, which is in good agreement with the AME12 value. A new recommended value of $\ensuremath{-}48\phantom{\rule{0.16em}{0ex}}331.6\phantom{\rule{0.16em}{0ex}}(49)\phantom{\rule{4.pt}{0ex}}\text{keV}$ is given.

The excitation function for the fusion–evaporation reaction Si 28 + Ni 64 has been measured down to a cross section of 25 nb. This is the first observation of fusion hindrance at extreme sub-barrier energies for a system with a small, negative Q-value ( − 1.78 MeV ). This result is further proof that heavy-ion fusion hindrance, reported earlier only for systems with large, negative Q-values, is a general phenomenon. The measured behavior can be reproduced by coupled-channels calculations with a modified ion–ion potential incorporating the effects of nuclear incompressibility.

A new focal-plane detector system has been designed and constructed for measuring very small heavy-ion induced fusion-evaporation cross sections with the Fragment Mass Analyzer (FMA) at Argonne National Laboratory. The system has been tested and successfully used in a fusion-evaporation excitation function measurement for 64 Ni + 100 Mo down to the 5 nb level. The design and performance of the detector system are described in detail with some examples from the latest data. Besides excellent tracking capabilities for each event measured in the detector, suppression of scattered beam background of the order of 4 × 10 - 17 has been demonstrated.

The in vivo immunoregulatory effect of anergic cells induced by blocking the costimulatory pathway was investigated in this study. Anergic cells were generated in vitro by mixed culture of murine splenic cells from BALB/c and C3H/HeJ under the blockade of anti-CD154 and anti-CD80 monoclonal antibodies, and the in vitro activity of anergic cells were observed. The 3.0 Gy gamma-irradiated BALB/c mice received cardic allografts from C3H/HeJ, and anergic cells were intravenously injected immediately after transplantation. Recipient mice injected with anergic cells also received rapamycin therapy (1 mg/kg/day) for 14 days. On day 7 after transplantation, the subsets of peripheral blood T lymphocytes, the pathology of grafts and the infiltration of lymphocytes in grafts were analysed. Untreated gamma-irradiated animals showed a graft median survival time (MST) of 9 days. Animals injected with anergic cells only or receiving rapamycin therapy alone showed MST of 11 and 17 days, respectively. MST of allograft in mice treated with control cells plus rapamycin therapy was 9 days. Animals injected with anergic cells plus rapamycin therapy, but receiving third-party allografts (C57BL/6J), showed an MST of 15 days. However, anergic cell injection plus rapamycin therapy prolonged allograft survival significantly (MST 28 days, P0.01). The rejection was mild and tissue architecture was preserved in recipient mice receiving anergic cell injection plus rapamycin therapy. Furthermore, anergic cells and rapamycin therapy decreased the percentage of peripheral blood CD4+ and CD8+ T cells (including CD25+, CD152+, CD154+ and CD28+ subsets) and greatly reduced the infiltrating lymphocytes in allografts (including CD3+, CD4+, CD8+ and CD25+ T cells). In conclusion, the treatment based on anergic cells' adoptive transfer plus rapamycin therapy demonstrated a significant prolongation of murine cardiac allograft survival in a donor antigen-specific manner. This therapeutic protocol alleviated allograft rejection to solid allograft in vivo.

The (8)B(alpha,p)(11)C reaction is part of the network that can bypass the triple a process leading to the production of (12)C. We have measured the astrophysical reaction rate for this reaction by studying the inverse (11)C(p,alpha)(8)B process. The radioactive (11)C beam was produced via the p((11)B,(11)C)n reaction using the in-flight facility at the ATLAS accelerator. The astrophysical reaction rate obtained from the excitation function measured in the energy range E(x)=8.8-10 MeV was found to be a factor of 10-50 higher than previous estimates.

As one of low temperature superconducting materials, multifilamentary Nb3Sn strand is an ideal choice for high-field superconducting magnets (>10 T). The International Thermonuclear Experimental Reactor (ITER) has special requirements for the Nb3Sn strands: high critical current density and low hysteresis loss. Multifilamentary Nb3Sn strand with high performance has been developed by bronze process. The highest non-Cu Jcn(12 T, 4.22 K, 0.1 ?V/cm) value of 812 A/mm2 has been obtained. The hysteresis loss of the strand is 380 mJ/cm3 with 650°C ×100 h. The properties of the Nb3Sn strand can meet the specifications proposed by the ITER project.

We have measured the fusion cross sections of the 12C(13C, p)24Na reaction through off-line measurement of the beta-decay of 24Na using the beta-gamma coincidence method. Our new measurements in the energy range of Ec.m. = 2.6-3.0 MeV do not show an obvious S-factor maximum but a plateau. Comparison between this work and various models is presented., Comment: 3 pages, 3 figures, Talk at the "10th International Conference on Nucleus-Nucleus Collisions", Beijing, 16-21 August 2009

A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the (α, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for (α, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only (α, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. × 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the (α, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the (α, p) reaction to reach the anode segment below the reaction.

Fusion-evaporation reactions induced by 110 MeV B-11 and radioactive C-11 on Rb-87 targets have been studied by measuring evaporation residue-light particle coincidences. The proton to alpha particle ratio in each reaction has been derived and compared with predictions from statistical model calculations. These calculations account rather well for the experimental data, when a small empirical adjustment of the emission barrier is performed, in agreement with earlier results. No evidence is found for predicted temperature and isospin modification of the binding energies. The possibility of a further study of isospin and temperature dependent effects in fusion-evaporation reactions with radioactive beams is discussed.