Science
The DRAGON Facility at TRIUMF-ISAC: Installation Status and Commissioning Plans
This report provides a status report of the construction and installation of the DRAGON facility and as well provides information on what is required in terms of both stable and radioactive beams for the commissioning of DRAGON and the first planned experiment, E824, the study of 21Na(p,γ)22Mg reaction. Assuming a 21Na beam intensity of 1010/s, 54 beam shifts are requested for this study.
Journal: EEC Report
The DRAGON Facility at TRIUMF-ISAC Status and Plans
The primary purpose of the DRAGON (Detector of Recoils And Gammas Of Nuclear reactions) facility is to measure the astrophysical S-factor or resonance strengths in radiative proton and alpha capture reactions. These reactions will be studied using inverse kinematics with gaseous targets of hydrogen or helium, and heavy ions with center of mass energies from 0.15 to 1 MeV/u. Since the facility is located at TRIUMF-ISAC, these heavy ions will consist primarily (but not exclusively) of short-lived radioactive species and the reactions are of interest to the increasing our understanding of the process of explosive nucleosynthesis in nova, supernova, and x- ray bursts. Funding for the DRAGON Facility was received April 1998 and the present plans are to initiate commissioning in the summer of 2000. The purpose of this report is to give the TRIUMF Experimental Evaluation Committee a report on the status of the building program, and the plans for the experimental program.
Journal: EEC Report
DRAGON Q1, Q2 Alignment: November 2007
The vertical positions of DRAGON quadrupoles Q1 and Q2 were adjusted on November 27 and 28, 2007. This report presents the evidence that their heights were wrong, the methods used to monitor quad positions and the results of the adjustment.Those taking part in the exercise were C. Ruiz, P. Machule, C. Vockenhuber, U. Hager and the author. Valuable technical advice was given by B. Gasbarri and M. Jansz.
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Determining DRAGON's acceptance: a Microscopic view
DRAGON measures the resonance strengths of nuclear reactions using beams from the ISAC facility, this resonance strength is fundamental in calculating the rates at which elements are created and destroyed in the interior of stars and during explosions like supernovae and novae. A key component of the resonance strength is the yield mea- surement. For an accurate measurement of the yield, various efficiency fractions must be known including the efficiency of the DRAGON mass spectrometer. This report presents measurements taken with a 148Gd α-source mounted in the gas target of DRAGON, this simulates a reaction with a cone angle of ≈ 20 mrad. A collimator is used that allows a microscopic view of particle transmission in DRAGON. Results suggest that the gas target box axis is lower than the separator axis by ≈ 2 mm, Q1’s ’standard’ setting is high by ≈ 5%, there is a possible quadrupole misalignment between the two electric dipoles of DRAGON which decreases the transmission of particles emitted to the left (looking upstream), and finally there is a possible misalignment that causes a x − y correlation at the final slits. Simulations with GEANT have been performed to test these conclusions with mixed results. Conclusions and recommendations are presented.
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DRAGON summer research report: charge state distributions after radiative capture
DRAGON Measurements of the charge-state distribution (CSD) of a 1.068 MeV/u C beam in He, and of the 6+:5+ charge-state population ratio in the recoils of the 12C(α,γ)16O reaction are reported. A computer simulation was developped to model the CSD of both beam and recoil par- ticles in inverse kinematics experiments. The code was used to model this reaction, and the results are compared to data from DRAGON and from ERNA. The simulation was in good agreement with the DRAGON data and with recoil data from ERNA. The results suggest that, for this fu- sion reaction on the Jπ=4+ resonance at Ebeam = 1.064 MeV/u, the recoil ions contain only the nucleons and not the electrons of the target He atom.
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DRAGON summer research report: differential pumping system
Constraints on the differential pumping system of the DRAGON are discussed, as are the weak- nesses in the current design. An attempt is made to improve the system, so as to allow for a 30 mrad acceptance half-angle with a 4 mm beam spot size, and the production of recoils up to 1 cm upstream from the target center. Three new designs are presented. The new systems use either the same number of pumps as the exising one or require the purchase of 1-2 new turbo pumps. The new pumping systems are around 45 cm shorter than the existing one; this extra space could be used to incorporate another magnetic quadrupole doublet or a post-stripper gas cell into the DRAGON.
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