33 Matching Results

Search Results

Advanced search parameters have been applied.

EXPERIMENTAL PROBLEMS IN THE USE OF A POLARIZED PROTONTARGET

Description: I have understood my assignment as a review of some of the work done in high-energy physics with polarized proton targets and a description of some of the special problems connected with polarized targets. Most of my report will be based on the polarized target that I am most familiar with--that constructed by Jeffries, Schultz, Shapiro, and myself. This target is no longer unique; in fact, it is now somewhat old-fashioned in some respects. Other polarized proton targets are in operation at CERN, Saclay, the Rutherford Laboratory, Argonne National Laboratory, the Soviet Union, and there is a target newly in operation at the Brookhaven Laboratory. Other targets are in operation or are in the process of design or construction at a number of other places. Unfortunately, none of these targets consists of pure hydrogen. The target material most often used is made of lanthanum magnesium nitrate, LMN. About a quarter of the weight of this crystal is water; it is the protons within the water molecules that are polarized. Hydrogen constitutes only 3 percent of the weight of the crystal. This means that scattering processes on hydrogen must be distinguished kinematically from scattering processes involving the heavy elements of the target if the target is to be used efficiently in high-energy scattering experiments. In fact, some of the experiments one would very much like to do appear to be very difficult. In LMN the protons are polarized by an indirect process known as dynamic polarization. Neodymium ions are added to the crystal when it is grown from a water solution. The neodymium ions are substituted for lanthanum to the extent of one percent or less. The neodymium ion has an odd number of electrons; it has a doublet ground state, called a Kramers doublet, that acts very much like a ...
Date: September 9, 1966
Creator: Chamberlain, Owen
Partner: UNT Libraries Government Documents Department

Optics of High-Energy Beams

Description: Many of the experiments now being conducted on high-energy accelerators requires the use of beams of charged secondary particles. It is worth while at this time to attempt to summarize information about some of the most useful methods of setting up such beams. We are not concerned here with the primary beam of the accelerator. Rather, they assume that a target is struck by the primary beam and that it is desired to form a beam from the secondary charged particles that emerge from collisions within the target. The simplest system of forming this beam of secondary particles involves the use of magnetic fields only. In most cases it is desirable to obtain a beam of particles of known magnetic rigidity, or momentum. The bulk of this article is addressed to this problem. Some comments are also made about the use of electric fields in conjunction with magnetic fields. The inclusion of electric fields allows the separation of a beam of known momentum into its various components according to the velocities of the particles, hence according to the masses of the particles. These are referred to as ''separated beams''.
Date: May 1, 1960
Creator: Chamberlain, Owen
Partner: UNT Libraries Government Documents Department

Summary - Bevatron Research Meeting II

Description: The operational characteristics of the Cosmotron were reviewed in brief. Since a rather complete account of this machine is now available in the September 1953 issue of Rev. Sci. Inst., this summary will include only the more recent utilization of the machine as a research instrument.
Date: October 13, 1953
Creator: Chamberlain, Owen
Partner: UNT Libraries Government Documents Department

HIGH-ENERGY-PHYSICS EXPERIMENTS WITH POLARIZED TARGETS

Description: If we are to do a workmanlike job of studying the strong interactions it is imperative that we have knowledge of the spin dependence of the forces. This implies that polarization experiments are essential. Already Bareyre, Bricman, Stirling and Villet have shown that pion-proton polarization experiments should be interpreted as indicating two new resonances not previously seen by other methods. The present-day approach to determining detailed pion-proton scattering amplitudes is to use measured differential cross sections, polarization measurements, dispersion relations, and isospin conservation rules. Further assumptions are unitarity of the S matrix and the short-range nature of strong interactions. In the more distant future I hope we may see the day when the scattering experiments will be sufficiently detailed that the dispersion relations will not be necessary to the interpretation of results. Then the dispersion relations may themselves be checked experimentally, rather than being assumed. I see, then, an early period of polarization experiments followed by a later period in which more extensive experimental results will be called for. For the pion-proton system the first period seems well progressed, based on measurements of differential cross section and P, the polarization. In the second period more complex experiments should be required, such as measurements of the parameters R and A . In R and A measurements, the protons have a known polarization before the collision takes place. After the pion scatters on the proton, one asks how much residual polarization the proton has. The nucleon-nucleon (N-N) system is susceptible to similar analysis, but there are more amplitudes to be determined, so more experiments must be performed. The N-N system is less well analyzed at present than the {pi}-N system.
Date: December 1, 1966
Creator: Chamberlain, Owen
Partner: UNT Libraries Government Documents Department

Recent Advances in Millimicrosecond Counting Techniques

Description: The author describes some of the changes that are now occurring or are likely to occur quite soon in the fast counting techniques. The author draws heavily on the information and advice of Dr. Clyde Wiegand and Mr. Quentin Kerns of the University of California Radiation Laboratory. The techniques the author mentions should be quite useful in several different types of experiments. The fast conicidence techniques are principally used for reducing background from accidental coincidences, for measuring times of flight of particles from one counter to another, and for measuring the life times of unstable particles.
Date: April 17, 1956
Creator: Chamberlain, Owen
Partner: UNT Libraries Government Documents Department

Elastic Scattering of 190 MEV Deuterons by Protons

Description: The elastic differential scattering cross section of 190 MeV deuterons by protons has been measured from 15 degrees to 170 degrees in the center of mass system. The cross sections were obtained by subtracting the carbon counts from those received with a polyethylene target. Part I presents a description of the experiments. Results are shown in Table IV and Fig. 3. Part II compares these results with those expected from theory by making use of a method developed by Chew. A summary of this comparison is given in Table VII.
Date: June 3, 1953
Creator: Chamberlain, Owen & Stern, Martin O.
Partner: UNT Libraries Government Documents Department

Proton-Proton Scattering at 340 MeV

Description: Measurements of the proton-proton differential scattering cross section using 340 Mev protons show a cross section approximately constant between 41{sup o} and 90{sup o} in the center of mass system. Two methods of counting the scattered protons have been used. The first method uses a counter telescope to count the scattered protons. The second method utilizes coincidences between counters which record the two protons involved in a single scattering process. The first method gives slightly higher cross sections; the average value of the differential cross section is (5.5 {+-} 1.0) x 10{sup -27} cm{sup 2} steradian{sup -1} in the center of mass system. Although the scattering appears isotropic it is larger than can be accounted for with pure S-scattering. There is a strong suggestion, but no positive proof, that n-p and p-p forces are different.
Date: January 1, 1950
Creator: Chamberlain, Owen & Wiegand, Clyde
Partner: UNT Libraries Government Documents Department

The Velocity-Selecting Cerenkov Counter

Description: A number of varieties of velocity-selecting Cerenkov counters have been described by Dr. John Marshall. The authors will present a description of a counter different from any described by Marshall in his review article, but of the same type mentioned descriptively by Marshall in another article under the heading ''Cylindrical mirror counter without lens''. Some tests of this type of counter were carried out by S.J. Lindenbaum and L.C. Yuan. The counter we describe was developed for the detection of a small fraction of antiprotons in a beam of negative particles originating at the target of the Bevatron. As far as the authors are aware, this represents the first practical use of a velocity-selecting Cerenkov counter in an experimental investigation.
Date: April 17, 1956
Creator: Chamberlain, Owen & Weigand, Clyde
Partner: UNT Libraries Government Documents Department

Measurement of the Polarization in Elastic Electron ProtonScattering

Description: We have measured the (illegible) scattering (?-illegible) of electrons (?-illegible) from a polarized proton target. (illegible) between (?-illegible) imaginary part of the two-photon-(illegible) (illegible) photon-exchange amplitude could produce (?-illegible) (illegible) results indicate no asymmetry within (illegible) 1 to 2% at four(?-illegible)-momentum transfer (illegible) (illegible) 0.98 (GeV/c){sup 2}.
Date: March 1, 1970
Creator: Powell, Thomas; Chamberlain, Owen & Borghini, Michel
Partner: UNT Libraries Government Documents Department

The Mechanism of Proton Polarization in High-EnergyCollisions

Description: Recently experimental evidence has accumulated showing that high-energy collisions of protons with various nuclei induce a considerable polarization in proton beams, and a mechanism has been proposed to account for this effect.
Date: June 9, 1954
Creator: Chamberlain, Owen; Segre, Emilio; Tripp, Robert; Wiegand, Clyde & Ypsilantis, Thomas
Partner: UNT Libraries Government Documents Department

Observation of Antiprotons

Description: One of the striking features of Dirac's theory of the electron was the appearance of solutions to his equations which required the existence of an antiparticle, later identified as the positron.
Date: October 19, 1955
Creator: Chamberlain, Owen; Segre, Emilio; Wiegand, Clyde & Ypsilantis,Thomas
Partner: UNT Libraries Government Documents Department

π<sup>+</sup>-p ELASTIC SCATTERING AT 310 Mev: PHASE-SHIFT ANALYSIS

Description: A comprehensive phase-shift analysis of {pi}{sup +}-p elastic-scattering data at 310-Mev incident-pion laboratory kinetic energy has been performed. The experimental data utilized include measurements of the differential and total cross sections and of the recoil-proton polarization. The D-wave phase shifts were found to be definitely needed in order to attain an adequate fit to the data. A general search for phase-shift solutions was carried out, using S-, P-, and D-wave phase shifts. One solution--of the Fermi type--was found that fits the data significantly better than any of the other solutions obtained. The calculated errors in the phase shifts of this set vary from 0.4 to 0.6 deg. Because it was felt that these errors might be deceivingly restrictive, the effects of small nuclear F-wave phase shifts on the results of the analysis were investigated and were found to be large; not only are the uncertainties in the original Fermi-type solution increased, but additional sets of phase shifts arise that fit the data well. One of these new solutions is similar to the original Fermi set except that the magnitudes of the phase shifts in this new fit are in general larger than those in the initial solution, and the signs of the D-wave phase shifts are reversed. The nuclear phase shifts in the original Fermi solution and their rms errors are (when F-wave phase shifts are allowed): S{sub 3,1} = -17.2 {+-} 2.6 deg, P{sub 3,1} = -2.9 {+-} 4.0 deg, P{sub 3,3} = 135.0 {+-} 0.6 deg, D{sub 3,3} = 3.1 {+-} 2.6 deg, D{sub 3,5} = -4.9 {+-} 2.1 deg, F{sub 3,5} = 0.5 {+-} 0.6 deg, F{sub 3,7} = -0.6 {+-} 1.4 deg. Although theory appears to favor this set, further theoretical and experimental evidence is desirable. The values given here for the first five phase shifts ...
Date: November 16, 1960
Creator: Foote, James H.; Chamberlain, Owen; Rogers, Ernest H. & Steiner, Herbert M.
Partner: UNT Libraries Government Documents Department

A Liquid-Hydrogen Cerenkov Counter

Description: Two models of a liquid-hydrogen (?-illegible) Cherenkov counter (illegible) been constructed (illegible). The first served as a prototype (?-illegible) and was (illegible) to demonstrate the feasibility (?-illegible) of the (illegible) concept (?-illegible) (illegible) liquid hydrogen does not give scintillation (?-illegible) (illegible) that of Cherenkov light. The second, final version (?-illegible), (illegible) in an experiment (?-illegible) in which particles brought to rest (?-illegible) (illegible) (illegible) electrons. In this second counter, the efficiency (?-illegible) (illegible) relativistic (?-illegible) particles (?-illegible) by their Cherenkov radiation in liquid hydrogen (?-illegible) was measured by stopping (illegible) mesons in the hydrogen and detecting their decay electrons outside (?-illegible) of the flask (?-illegible) after a suitable time delay. An average detection (?-illegible) efficiency (?-illegible) of 75% (?-illegible) was (illegible) taken over the volume of the hydrogen (?-illegible).
Date: May 9, 1963
Creator: Zipi, T.F.; Chamberlain, Owen; Kadyk, John A. & York, Carl M.
Partner: UNT Libraries Government Documents Department

Antiprotons

Description: Since the development of Dirac's theory of the electron and the brilliant confirmation of one of its most startling predictions by the discovery of the positron by Anderson, it has been assumed most likely that the proton would also have its charge conjugate, the antiproton. The properties that define the antiproton are: (a) charge equal to the electron charge (also in sign); (b) mass equal to the proton mass; (c) stability against spontaneous decay; (d) ability to annihilate by interaction with a proton or neutron, probably generating pions and releasing in some manner the energy 2 mc{sup 2}; (e) generation in pairs with ordinary nucleons; (f) magnetic moment equal but opposite to that of the proton; (g) fermion of spin 1/2. Not all these properties are independent, but all might ultimately be subjected to experiment.
Date: November 29, 1955
Creator: Chamberlain, Owen; Segre, Emilio & Wiegand, Clyde
Partner: UNT Libraries Government Documents Department

A POLARIZED PROTON TARGET

Description: We have successfully conducted a series of experiments involving scattering of high energy pions and protons from a target containing polarized protons. Results of some of these experiments were reported at this conference, and in the literature. Proton polarizations as high as 65% have been measured; the average polarization during sustained data-taking has been typically 45%.
Date: July 3, 1964
Creator: Chamberlain, Owen; Schultz, Claude & Shapiro, Gilbert
Partner: UNT Libraries Government Documents Department

Experiments on Antiprotons: Antiproton-Nucleon CrossSections

Description: In this paper experiments a r e reported on annihilation and scattering of antiprotons in H{sub 2}O , D{sub 2}O, and O{sub 2}. From the data measured i t i s possible to obtain an antiproton-proton and a n antiproton-deuteron c r o s s section a t 457 Mev (lab). Further analysis gives the p-p and p-n c r o s s sections a s 104 mb for the H-p reaction c r o s s section and 113 mb for the p-n reaction c r o s s section. The respective annihilation cross sections a r e 89 and 74 mb. The Glauber correction necessary in order to pass from the p-d to the p-n c r o s s section by subtraction of the p-p c r o s s section i s unfortunately large and somewhat uncertain. The data a r e compared with the p-p and p-n c r o s s sections and with other results on p - p collisions.
Date: July 22, 1957
Creator: Chamberlain, Owen; Keller, Donald V.; Mermond, Ronald; Segre,Emilio; Steiner, Herbert M. & Ypsilantis, Tom
Partner: UNT Libraries Government Documents Department

Antiproton Interaction Cross Sections

Description: Using the 1.19-Bev/c antiproton beam recently discovered at the Berkeley Bevatron of the University of California, we have measured the attenuation cross section in beryllium and copper. These cross sections are compared to attenuation measurements made with the same geometry using positive protons of the same incident energy (497 MeV).
Date: February 27, 1956
Creator: Chamberlain, Owen; Keller, Donald V.; Segre, Emilio; Steiner,Herbert M.; Wiegand, Clyde & Ypsilantis, Tom
Partner: UNT Libraries Government Documents Department