Particle detection at REX-ISOLDE and the d(30Mg, 31Mg)p reaction

Due to the production and acceleration method for radioactive ions at REX-ISOLDE, a newly commissioned accelerator, there are three sources for beam contamination: isobaric contamination from the ISOLDE target, isobaric contamination from β-decay while the ions are captured in the REXtrap and charge bred in the EBIS, and stable contamination from the residual gas in the EBIS if the mass to charge ratio allows it to pass the mass separator of REX. In order to determine the beam contamination qualitatively and quantitatively two 10 μm thick silicon pin-diodes were installed in the beamline behind the target chamber in September 2004. The results of measurements with exotic 30Mg and 32Mg beams are presented in the first part. In the second part a partial analysis of an experiment employing the(d, p) reaction in inverse kinematics with a 30Mg beam is presented. The aim of this experiment was to study the level scheme of 31Mg and to get additional information about the spin and parity of its states via the angular distribution of the protons emitted

T-REX

Transfer reactions in inverse kinematics using the radioactive ion beams provided by the REX-ISOLDE facility at CERN are very good tools to gain insight into the single-particle properties of exotic nuclei. The new silicon particle detector setup T-REX, optimized for these transfer reactions, is presented in this article. T-REX consists of position sensitive ΔE-E telescopes in a compact configuration that covers up to 66% of the solid angle. The setup allows the identification of the light reaction products and the measurement of their angular distribution for a large range of polar angles. Simultaneous detection of the elastically scattered target-like nuclei enables the determination of the optical model parameters used in the analysis of the experiments

GRIFFINCollaboration/GRSISort: Overdue Ozelot

<p><strong>New</strong></p> <ul> <li>grsiframe: Replacement for grsiproof, based on ROOT's RDataFrame instead of the obsolete PROOF. grsiframe uses "helpers" instead of "selectors" and a number of the latter that have been translated into the former can be found in the examples directory.</li> <li>FastTiminingHistSelector: A selector to create fast timing histograms from a prepared tree of fast timing information.</li> <li>checklog.sh script in examples is a quick script to check a log-file to see if the sort of a subrun ended successfully or not. Simply checks if the last line is "bye,bye" (good) or "Deleting thread" (bad).</li> <li>sort.sh script in examples can be used to sort files and can be run with multiple instances in parallel. Automatically saves the output of the sorting into log files which can be check with checklog.sh script to see if the sorting finished.</li> <li>TLevelScheme: New class to create, plot, and save level schemes. Includes some modification to the behavior of GCanvas if the canvas name is "LevelScheme".</li> <li>TEfficiencyCalibrator: New GUI to automatically take spectra created by the effiency helper to calculate efficiency curves, including summing in and summing out. The calculation of the latter still has some bugs in it.</li> <li>TRedirect class redirect stdout and stderr to a file as long as the object exists, i.e. until it goes out of scope or is deleted.</li> <li>EnableCrosstalkCorrection program allows enabling crosstalk correction for a list of analysis files.</li> <li>PlotVsRun allows plotting histograms vs the run number.</li> <li>ReadCalFromRoot loops over the provided root files and writes out a .cal file for each one of them.</li> <li>SetOdbFromData loops over the provided root files and checks if the PPG information read from the ODB matches the data. Writes out a line for each file whether the information was already correct, some error occured, or if it was updated.</li> <li>checkSort loops over the provided analysis root files and checks if any problem with repeated events occured (the bug making this check necessary has been fixed by now).</li> </ul> <p><strong>Improvements</strong></p> <ul> <li>TGRSIUtilities now provides a trim function and the separate versions in GValue, TChannel, and TRunInfo have been removed.</li> <li>GValue: It is now possible to provide a default value to <code>GValue::Value</code> which is used instead of <code>NaN</code> if the requested value is not found.</li> <li>Globals.h now provides a function <code>std::string hex(T val, int width = -1)</code> that formats the provided value in hexadecimal with lead 0x and if the provided width is positive pads it with zeroes up to that width. It also provides a <code>void SetGRSIEnv()</code> function to set the environment for grsisort, and for linux systems a <code>void PrintGdbStacktrace()</code> function to print the stack trace using gdb.</li> <li>TSinglePeak and all its children now have a working Sigma and FWHM function, and the <code>InitializeParameters</code> function can take a range which is used as limits for the centroid.</li> <li>TPeakFitter uses the range as limit for the centroid and doesn't include it when releasing all parameters if the fit failed to give good errors. Also returns the <code>TFitResultPtr</code> to allow users to access e.g. the covariance matrix.</li> <li>Made some adjustments to make grsisort work with ROOT 6.24 and 6.26.</li> <li>TCalibrationGraphSet: Added options to set marker type, as well as setting line colors and marker colors in one single function and adding axis titles. Also added functions to get minimum and maximum x- and y-values. When adding graphs to the set, the colors are initialized to the current size of the set.</li> <li>TChannel now supports multiple ranges for calibrations, corrections for time drifts (if digitizer clocks are not synched properly) and added GetTime function which is now called by <code>TDetectorHit</code> and simply calles the GetTime function of the mnemonic.</li> <li>TMnemomic warns if the base class is being used instead of the version defined in the data library. Also includes GetTime function that takes care of the different time stamp units of different digitizer etc.</li> <li>Instead of looping over the vector of fragments and adding the fragments on at a time to the <code>UnpackedEvent</code> class, we now simply set the raw data to the whole vector at once.</li> <li>TGRSIMaps includes a function to emplace elements.</li> <li>Added multiple new options to grsisort, mostly used by grsiproof and grsiframe.</li> <li>TGRSISelector includes a check for the size of object to warn if ROOT's limit of 1 GB is reached.</li> <li>Replaced (most?) uses of <code>printf</code> with <code>std::cout</code>.</li> <li>TNucleus offers option to get the transition sorted by energy or intensity. To that effect two lists of transitions are kept simultaneously.</li> <li>TPulseAnalyzer has been ported to the latest version from SFU TIPSort code.</li> <li>Updated TScaler to get ratio of two variables of the last scaler entry (used in EMMA). Also scalers are now actually written to file at the end.</li> <li>TSortingDiagnostics now includes a map of channels missing in the calibration file.</li> <li>TSourceCalibration zooms graph and residual simultaneously, had some bugs fixed as well.</li> <li>Improved and unified <code>Print</code> statements for detectors.</li> <li>TRunInfo now has a function <code>CreateLabel</code> that returns a string created using the run and sub-run numbers in it. Before this code was copied in multiple places of grsisort.</li> <li>Added new event building mode "Skip" that skips the step of sorting the fragments because they are already sorted.</li> <li>The makefile honors the c++ standard root-config returns and includes support for HIL data library.</li> <li>WriteCalToRoot output updated to show more clearly which files were update successfully and where problems occured.</li> </ul> <p><strong>Bug fixes</strong></p> <ul> <li>grsiproof: <code>--max-events</code> flag now works, additional options for PROOF added, log file names now include the run and sub-run number(s).</li> <li>The use of multiple threads to write the analysis file has led to problems with single events being repeated thousands of times, leading to spikes in the energy or time histograms. So we have reverted now to having TAnalysisWriteLoop write a single TFile directly instead of using the <code>TAnaysisWriteLoopClient</code> class.</li> <li>TPeakFitter used to crash when adding and removing peaks between fits.</li> <li>TSinglePeak and children now first set the parameter, then the limits, this avoids warnings that the parameter (which is 0 at that point) is outside the limits.</li> </ul&gt

The \u3csup\u3e33\u3c/sup\u3eS(p,γ)\u3csup\u3e34\u3c/sup\u3eCl reaction in classical nova explosions

The analysis of microscopic grains within primitive meteorites has revealed isotopic ratios largely characteristic of the conditions thought to prevail in various astrophysical environments. Recently, several grains have been identified with isotopic signatures similar to those predicted within the ejecta of nova explosions on oxygen-neon white dwarfs. A possible smoking gun for a grain of nova origin is a large 33S abundance: nucleosynthesis calculations predict as much as 150 times the solar abundance of 33S in the ejecta of oxygen-neon novae. This overproduction factor may, however, vary by factors of at least 0.01 - 3 because of uncertainties in the 33S(p,γ)34Cl reaction rate over nova temperatures. In addition, better knowledge of this rate would help with the interpretation of nova observations over the S-Ca mass region, and contribute towards the firm establishment of a nucleosynthetic endpoint in these phenomena. Finally, constraining this rate may help to finally confirm or rule out the decay of an isomeric state of 34Cl (Ex = 146 keV, t1/2 =32 min) as a source for observable gamma-rays from novae. Direct examinations of the 33S(p,γ)34Cl reaction in the past have only identified resonances down to Er = 434 keV. At nova temperatures, lower-lying resonances could certainly play a dominant role. Several recent, complementary studies dedicated to improving our knowledge of the 33S(p,γ)34Cl rate, using both indirect methods (measurement of the 34S( 3He,t)34Cl and 33S(3He,d) 34Cl reactions with the Munich Q3D spectrograph) and direct methods (in normal kinematics at CENPA, University of Washington, and in inverse kinematics with the DRAGON recoil mass separator at TRIUMF) are presented here. Our results affect predictions of sulphur isotopic ratios in nova ejecta (e.g. 32S/33S) that may be used as diagnostic tools for the nova paternity of grains. © ?Copyright owned by the author(s)

Shape coexistence in 94Zr studied via Coulomb excitation

In recent years, a number of both theoretical and experimental investigations have been performed focusing on the zirconium isotopic chain. In particular, state-of-the-art Monte Carlo shell-model calculations predict shape coexistence in these isotopes. In this context, the 94Zr nucleus, which is believed to possess a nearly spherical ground state, is particularly interesting since the purported deformed structure is basedon the low-lying 02+ state, making it amenable for detailed study. In order to provide definitive conclusionson the shapes of the low-lying states, two complementary experiments to study 94Zr by means of low-energy Coulomb excitation were performed. This data will allow the quadrupole moments of the 21,2+ levels to be extracted as well as for the deformation parameters of the 01,2+ states to be determined and, thus, definitive conclusions to be drawn on the role of shape coexistence in this nucleus for the first time. The first experiment was performed at the INFN Legnaro National Laboratory with the GALILEO-SPIDER setup, which, for the first time, was coupled with 6 lanthanum bromide scintillators (LaBr3:Ce) in order to maximize the γ-ray detection effciency. The second experiment was performed at the Maier-Leibnitz Laboratory (MLL) in Munich and used a Q3D magnetic spectrograph to detect the scattered 12C ions following Coulomb excitation of 94Zr targets

Shape coexistence in

In recent years, a number of both theoretical and experimental investigations have been performed focusing on the zirconium isotopic chain. In particular, state-of-the-art Monte Carlo shell-model calculations predict shape coexistence in these isotopes. In this context, the 94Zr nucleus, which is believed to possess a nearly spherical ground state, is particularly interesting since the purported deformed structure is basedon the low-lying 02+ state, making it amenable for detailed study. In order to provide definitive conclusionson the shapes of the low-lying states, two complementary experiments to study 94Zr by means of low-energy Coulomb excitation were performed. This data will allow the quadrupole moments of the 21,2+ levels to be extracted as well as for the deformation parameters of the 01,2+ states to be determined and, thus, definitive conclusions to be drawn on the role of shape coexistence in this nucleus for the first time. The first experiment was performed at the INFN Legnaro National Laboratory with the GALILEO-SPIDER setup, which, for the first time, was coupled with 6 lanthanum bromide scintillators (LaBr3:Ce) in order to maximize the γ-ray detection effciency. The second experiment was performed at the Maier-Leibnitz Laboratory (MLL) in Munich and used a Q3D magnetic spectrograph to detect the scattered 12C ions following Coulomb excitation of 94Zr targets