Measurement of nuclear cross sections at astrophysical energies involving unstable species is one of the most challenging tasks in experimental nuclear physics. The use of indirect methods is often unavoidable in this scenario. In this paper the Trojan horse method is applied for the first time to a radioactive ion beam-induced reaction studying the ${}^{18}\mathrm{F}(p,\ensuremath{\alpha}$)${}^{15}\mathrm{O}$ process at low energies relevant to astrophysics via the three-body reaction ${}^{2}\mathrm{H}{(}^{18}\mathrm{F},{\ensuremath{\alpha}}^{15}\mathrm{O})n$. The knowledge of the ${}^{18}\mathrm{F}{(p,\ensuremath{\alpha})}^{15}\mathrm{O}$ reaction rate is crucial to understand the nova explosion phenomena. The cross section of this reaction is characterized by the presence of several resonances in $^{19}\mathrm{Ne}$ and possibly interference effects among them. The results reported in literature are not satisfactory and new investigations of the ${}^{18}\mathrm{F}{(p,\ensuremath{\alpha})}^{15}\mathrm{O}$ reaction cross section will be useful. In the present work the spin-parity assignments of relevant levels have been discussed and the astrophysical $S$ factor has been extracted considering also interference effects.

First application of the Trojan horse method with a radioactive ion beam: Study of the 18 F(p,α)15 O reaction at astrophysical energies

Classical novae are the result of thermonuclear flashes of hydrogen accreted by CO or ONe white dwarfs, leading eventually to the dynamic ejection of the surface layers. These are observationally known to be enriched in heavy elements, such as C, O and Ne, that must originate in layers below the H-flash convection zone. Building on our previous work, we now present stellar evolution simulations of ONe novae and provide a comprehensive comparison of our models with published ones. Some of our models include exponential convective boundary mixing to account for the observed enrichment of the nova ejecta even when accreted material has a solar abundance distribution. Our models produce maximum temperature evolution profiles and nucleosynthesis yields in good agreement with models that generate enriched ejecta by assuming that the accreted material was pre-mixed. We confirm for ONe novae the result we reported previously, i.e. we found that 3He could be produced in situ in solarcomposition envelopes accreted with slow rates (M < ˙ 10−10 M yr−1) by cold (TWD < 107 K) CO WDs, and that convection was triggered by 3He burning before the nova outburst in that case. In addition, we now find that the interplay between the 3He production and destruction in the solar-composition envelope accreted with an intermediate rate, e.g. M˙ = 10−10 M yr−1, by the 1.15 M ONe WD with a relatively high initial central temperature, e.g. TWD = 15 × 106 K, leads to the formation of a thick radiative buffer zone that separates the bottom of the convective envelope from the WD surface. We present detailed nucleosynthesis calculations based on the post-processing technique, and demonstrate in which way much simpler single zone T and ρ trajectories extracted from the multi-zone stellar evolution simulations can be used, in lieu of full multi-zone simulations, to analyse the sensitivity of nova abundance predictions on nuclear reaction rate uncertainties. Trajectories for both CO and ONe nova models for different central temperatures and accretion rates are provided. We compare our nova simulations with observations of novae and pre-solar grains believed to originate in novae.

MESA and NuGrid simulations of classical novae: CO and ONe nova nucleosynthesis

Crucial information on novae nucleosynthesis is linked to the abundance of 18F , which, due to great improvements in gamma-ray astronomy, can be detected in explosive environments. Therefore, the reaction network producing and destroying this radioactive isotope has been extensively studied in the last years. Among those reactions, the 18F(p,
 $\alpha$
 )15O cross section has been measured by means of several dedicated experiments, both using direct and indirect methods. The presence of resonances in the energy region of astrophysical interest has been reported by many authors. In the present work a report on a recent experiment performed via the Trojan Horse Method (THM) is presented and the results are given and compared with the ones known in the literature, both direct and indirect. Data arising from THM measurements are then averaged and the reaction rate calculated in the novae energy range.

Trojan Horse measurement of the 18F(p,$\alpha$)15O astrophysical S(E)-factor

The Trojan Horse Method (THM) represents an indirect path to determine the bare nucleus astrophysical S-factor for reactions among charged particles at astrophysical energies. This is achieved by m...

https://www.annualreviews.org/doi/pdf/10.1146/annurev-nucl-102419-033642

The Trojan Horse Method: A Nuclear Physics Tool for Astrophysics

The SuperORRUBA (Oak Ridge Rutgers University Barrel Array) of double-sided silicon strip detectors has been constructed at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). The array will primarily be used to study single-nucleon transfer reactions in inverse kinematics at exotic beam facilities. The detector exhibits good intrinsic energy resolution ( ∼ 25 keV ) and large solid-angle coverage over the polar angular range 55–125°. The detector is now in routine use and has been used for several measurements at the HRIBF.

Construction and commissioning of the SuperORRUBA detector

Simultaneous measurement of the proton-transfer {sup 18}F(d, n){sup 19}Ne and neutron-transfer {sup 18}F(d, p){sup 19}F reactions were performed with a {sup 18}F radioactive beam at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The experiments clarify the nuclear structure of {sup 19}Ne near the proton threshold, which is relevant for understanding the rates of proton-induced reactions on {sup 18}F in novae. Analogs for several states in the mirror nucleus {sup 19}F have not yet been identified in {sup 19}Ne, indicating that the level structure of {sup 19}Ne in this region is incomplete. We observed 15 levels in {sup 19}Ne from the {sup 18}F(d, n){sup 19}Ne measurement and 18 levels in {sup 19}F from the {sup 18}F(d, p){sup 19}F measurement. Angular distributions were extracted for all strongly populated states and compared to distorted-wave Born approximation calculations. The angular distributions for all the known states in the two nuclei determined in this work are consistent with their previously assigned spins and parities. The spectroscopic factors determined for these levels in the two nuclei are reported.

/pdf/single-nucleon-transfer-reactions-on-18-f-3s1mla2cxn.pdf

Single-nucleon transfer reactions on 18 F

The ${}^{18}\mathrm{F}(p,\ensuremath{\alpha}){}^{15}\mathrm{O}$ reaction is the predominant destruction mechanism in novae of the radionuclide $^{18}\mathrm{F}$, a target of $\ensuremath{\gamma}$-ray observatories. Thus, its rate is important for understanding $^{18}\mathrm{F}$ production in novae. We have studied resonances in the ${}^{18}\mathrm{F}+p$ system by making a measurement of a proton-transfer reaction ${}^{18}\mathrm{F}(d,n)$. We have observed 15 $^{19}\mathrm{Ne}$ levels, 5 of which are below the proton threshold, including a subthreshold state, which has significant ${l}_{p}=0$ strength. Our data provide a direct determination of the spectroscopic strength of these states and new constraints on their spins and parities, thereby resolving a controversy, which involves the 8- and 38-keV resonances. The ${}^{18}\mathrm{F}(p,\ensuremath{\alpha}){}^{15}\mathrm{O}$ reaction rate is reevaluated, which takes the subthreshold resonance and other new information determined in this experiment into account.

/pdf/first-proton-transfer-study-of-18-f-p-resonances-relevant-4kvomyd0mi.pdf

First proton-transfer study of 18 F + p resonances relevant for novae

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

N. D. Smith

Author Tools

Chat about Author

Papers

Single-nucleon transfer reactions on 18 F

First proton-transfer study of 18 F + p resonances relevant for novae