This procedure eliminated most of the error due to uncertainty in the beam energy.
THE GAMMA-RAY MEASUREMENTS 1. Introduction
After a short delay (150 ms) to ensure that the beam had disappeared, gamma rays were sequentially stored in the first and second memory halves of a pulse height. The ratio of the background-corrected count numbers in the two halves of the memory allows one to estimate the half-life of the gamma rays seen. Most of the large peaks in the high spectrum (the total delayed gamma-ray yield in the first two seconds after the beam is turned off) are due to gamma rays from s34 which follow the beta decay of the isomeric state of c134 to 0.
This made it possible to determine the energies of other visible gamma rays with an accuracy of 14 keV or better. Note that the s34 gamma rays have completely disappeared, illustrating the advantages of this method for finding gamma rays produced by the decay of short-lived radioisotopes. We eliminated this possibility by observing that 0. the spectrum produced by Na22. A source inserted in a beryllium chamber was examined using a detection geometry similar to that of the actual experiment.
A lower limit on the intensity of the beta branch to the O. 67-MeV level can be obtained by comparing the yields of the O. 51-MeV gamma rays in the difference spectrum. This is only a lower limit because much of the short-half-life O. 51-MeV radiation comes from other sources such as the beta decay of the ground state of c134. 67-MeV level which according to Glaudemans et al. 1964) decays 80% of the time directly to the ground state and falls through the O.
Our eventual solution was to "range-limit" the gamma rays using a small cylinder (1.27 cm diameter, O. 63 cm thick) of NE102 plastic scintillator (supplied by Nuclear Enterprises Ltd., Winnipeg, Canada) and create u· that due to the fact that the rate of energy loss for proton returns is greater than for Compton scattered electrons. Thus, in this part of the scintillator, the maximum pulse height that an electron could produce was less than that of the more energetic proton returns. Despite the poor statistics, due to the extreme inefficiency of the neutron detector, two gamma rays, of energies 1, are seen.
Both papers were cyclotron studies of the angular scattering of alpha particles inelastically scattered by Ca 40. The 35 MeV state represents a general rearrangement of the internal structure as suggested in the first paragraph, members of a. A suggested rotating band test would be to see if a member of the triad is at 5.
APPENDIX 1 Sample Calculations of the Si 28
Further evaluation of the absolute cross section will be considered for the two neutron sources separately. In the following calculation, numbers are taken, if necessary, from Figures 9 and 11, where the symbols used are defined unless they are defined above or are obvious.
APPENDIX 2
Within the terminal it passes through another narrow, gas-filled channel (the stripper channel), where much of the beam is stripped to a positive charge state and re-accelerated upon exiting the terminal. The purpose of the hydrogen was to reduce wear on the tungsten filament in the ion source. In an attempt to determine which was the best of the many different negative oxygen beams emanating from the source, we measured the 20° magnetic flux versus beam intensity at the Faraday cup near the low energy end of the tandem (i.e. at the low energy T-piece or LAAT).
All the peaks under a magnetic current of 100 ma are due to hydrogen rays since the same curve is obtained with only hydrogen in the source. The relative size of the different peaks depends on the lens settings, especially the setting of the Einzel lens mentioned above. 3 + comes from the source and H- comes around the 20° magnet (the H3 + /H- bundle), in accordance with a note in the INEC instruction manual.
Winkler, who noted that the H0 /H peak has maximum intensity at much higher settings of the exchange gas and the Einzel lens than the other hydrogen beams. He concluded that the H0/H beam was produced in the exchange channel by bombardment of the exchange gas. Due to the poor vacuum, a large number of charge exchange collisions could take place between the sulfur jet and the argon gas along the entire length of the high-energy acceleration column.
Thus, a small fraction of the sulfur and argon produced at lower charge conditions than that of the regulated sulfur beam will have the correct energy to get around the magnet. 2S or something derived from it forms a deposit on the ceramic balls which provides insulation for the parts of the ion source at 40 keV. It was discovered that the interval diameter of the exchange channel was reduced two-fold by the formation of a metal deposit.
The solid curve, which was used in our analysis, allows weakening of the primary curve. The shape of the efficiency integrals for the two curves is shown in the figure; nHCJH and llcac are. The standard deviation on the absolute value of the cross section is 20%; the statistical error at each point is.
The upper part of the pulse height spectrum resulting from neutron-induced reactions in a silicon semiconductor detector. Using the known Compton scattering cross section and the theoretical shape of the Compton profile {dashed curve), the active volume of the detector was found to be 0.
RADIATION
Spectrum produced in a silicon detector of neutrons from the reaction D(d, n)He3 at a bombardment energy of 5. After correction for the gas cell entrance foil, deuterium gas target thickness and kinematic energy spread of the outgoing neutrons, the average neutron energy at the detector was 8. This is a typical spectrum from the data used to obtain the Si28 + n yield curves in Figures 12 and 14.
A correction of 17%, taken from the data of Sattler (196 5), was applied to allow for the pulse height defect of the recoil silicon atoms. After correction for the Be 9. equivalent to 49 keV) and kinematic energy distribution of the outgoing neutrons, the average neutron energy at the detector was 13.
CH A NNEL NU M BER
It agrees well, both in absolute cross section and shape, with the curve of Fig. 2 in the ·overlap region (Ea. = 5-6 MeV) and with the data of Risser, Price and Class (1957), who measured this cross section for 1 .The two graphs show the number of scattered protons per unit incident charge as a function of the energy of the scattered proton, the latter being given by See Fig. 5 for the spectrum of a single monoenergetic neutron, in which the peaks are more clearly associated with the corresponding nuclear reactions in silicon that produce them.
0 peak arises in the same way as the dip in the Si26 spectrum (see Figure 22 and the discussion of artificial dips on page 53). See Figure 22 for the notation and see page 55 for a discussion of the results. detector at o0 at a bombardment energy of 10. The lower spectrum shows the same peaks with the center of the detector at 45°, with the front subtending an angle of 10. °.
Note that the neutron descent to the ground state cannot extend below the 255 channel due to the presence of groups from Be9. 0 peaks of the latter two are shown in the upper spectrum between channels 200 and 225. The deductions and results obtained are discussed beginning on page 59. Bottom right: One of the Be 9. a., n) spectra used for neutron calibration group leading to the Zn BU ground state.
The first three peaks of the Si28. n, a.) spectrum produced by the neutron group up to the first excited state of Zn 60 . are clearly revealed. The vertical error bars are largely due to uncertainty in the relative variation of the Si28. The error on the absolute cross section is 30% and the error on the relative magnitude of the ground and first excited state neutron yields is 20%.
The upper curve is the total return in the first two seconds; bottom, return in the first minus return in the second. See page 55 for a description of ground and first excited state Q-value measurements of Ar 34 and pages 74-77 for measurements of the positron branch at 0. Center: Levels in the proposed rotational band with their energies redefined relative to o+, 3.
The 12-MeV state is an estimate of the error in the data of Bauer et al. Negative ion current at LET vs. 20° magnetic current measured with a mixture of 93% H2 and 7% o2 in the source, and H .
