Liquid Deuterium Target Research Articles

K Lo−K So regeneration on deuterium

The K L o−K S o regeneration on deuterium has been measured at the 70 GeV Serpukhov accelerator in a momentum region of 18– 50 GeV c . The measurements were performed by means of a 3 m long liquid deuterium target and an on-line spectrometer. The preliminary results on the energy dependence of the modulus and phase of the transmission regeneration amplitude are reported.

Photoproduction of neutral pions off neutrons in the energy region between 500 MeV and 900 MeV

The differential cross sections for the reaction γ + n → π 0 + n have been measured at pions angles of 45°, 60°, 105°, 120° and 140° in the c.m.s. for photon energies of 500–900 MeV. Both π 0 meson and recoil neutron from a liquid deuterium target were detected with a pair of Čerenkov counters combined with lead spark chambers and a hodoscope consisting of 16 modules of plastic scintillation counters. The experimental results were compared with the recent phenomenological partial-wave analysis, and indicate that the ratio of the isoscalar part to the isovector part of the resonant amplitude of B 2_(N′(1520)(D 13)) is only about 0.2, and that in the γ + n → π 0 + n reaction there is no remarkable enhancement due to the N′(1470)(P 11) resonance.

Cible à deutérium liquide

Abstract An original liquid deuterium target has been built at the Orsay Linear Accelerator Laboratory to study the interaction of monochromatic gamma rays of 400 MeV with deuterons. We give here the description and the performances of the target and of the automatic system which provides it with liquid deuterium during several weeks, without any human intervention.

A liquid deuterium target for the production of a monoenergetic neutron beam

A cryogenic liquid deuterium target has been constructed for use in the production of a “monoenergetic” neutron beam by the D(p,n) 2p reaction. The cryostat is refrigerated by liquid helium which is continuously transferred to the cryostat at low rates (≈ 1.0 1h). When used with protons of energies between approximately 20 and 50 MeV, the peak in the neutron energy spectrum lies in the energy range 18 to 47 MeV. The neutron beam is used in an experimental program measuring neutron cross sections.

Proton-Neutron Elastic Scattering on a Deuterium Target

We have tested the feasibility of measuring the ratio of proton-neutron to proton-proton elastic scattering using the second extracted proton beam of the Argonne ZGS and a liquid-deuterium target. The forward proton was detected by a 35-m-long spectrometer consisting of magnets and scintillation and \ifmmode \check{C}\else \v{C}\fi{}erenkov counters. The recoil nucleon was detected by a steel-scintillator sandwich counter. The efficiency of this counter was measured using tagged neutron in coincidence with the spectrometer and calculated using a Monte Carlo simulation of the nuclear cascade. A scintillation counter determined whether the recoil nucleon was charged or neutral. At a test point of ${p}_{0}=12.4$ GeV/c, ${\ensuremath{\theta}}^{*}=37\ifmmode^\circ\else\textdegree\fi{}$, and $t=\ensuremath{-}2.2$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$, we found a $\mathrm{pn}$-to-$\mathrm{pp}$ cross-section ratio of 1.05\ifmmode\pm\else\textpm\fi{}0.14. The $\mathrm{pp}$ cross section was ${(\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}})}_{\mathrm{c}.\mathrm{m}.}=5.8\ifmmode\pm\else\textpm\fi{}0.6$ \ensuremath{\mu}b/sr, and the $\mathrm{pn}$ cross section was ${(\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}})}_{\mathrm{c}.\mathrm{m}.}=6.1\ifmmode\pm\else\textpm\fi{}1$ \ensuremath{\mu}b/sr. The ratio of $\mathrm{pp}$ scattering from deuterium to $\mathrm{pp}$ scattering from hydrogen, corrected for geometrical effects, was 0.75\ifmmode\pm\else\textpm\fi{}0.09. We discuss the future of this technique for measuring $\mathrm{pn}$ cross sections and compare the results of the test with the predictions of the Glauber multiple-scattering formalism. We also plot available $\mathrm{pn}$ data as a function of ${{\ensuremath{\beta}}_{\mathrm{c}.\mathrm{m}.}}^{2}{{p}_{\ensuremath{\perp}}}^{2}$.

The Production Asymmetry in γ+n→π-+p Process with Polarized Photons

The production asymmetry in the reaction γ+ n →π - + p is measured at 90° in the center-of-mass system and at five photon energies from 357 to 555 MeV. Linearly polarized photons are obtained by means of the coherent breamsstrahlung process from a silicon single crystal. Negative pions and recoiling protons from a liquid-deuterium target are detected simultaneously so that events originated from neutrons almost at rest in the deuterons are selected. The asymmetry data are compared with the dispersion-relation calculation of Berends, Donnachie, and Weaver, and with that of Schmidt et al. It is shown that the contribution from the Roper P 11 (1470) resonance is small in the pion photoproduction process.

π−Photoproduction from Deuterium at Laboratory Energies 600 to 1250 MeV

The differential cross section for the reaction $\ensuremath{\gamma}+n\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}+p$ was measured for laboratory photon energies between 600 and 1250 MeV, using a liquid deuterium target. The internal nucleon momentum distribution of the deuteron was used to calculate the major effect of using deuterium as a neutron target. The data show that the amplitude to excite the ${F}_{15}(1688)$ resonance is small, in agreement with a recent quark-model prediction.

Measurements of Elastic Electron-Deuteron Scattering at High Momentum Transfers

Measurements of cross sections for elastic electron-deuteron scattering were made over a range of four-momentum transfers squared from 14.4 to 35.4 ${\mathrm{F}}^{\ensuremath{-}2}$. Incident electrons of energies 4.419 and 4.910 BeV were scattered from a liquid-deuterium target and detected in coincidence with the recoil deuterons. Measurements of a combination of the charge and electric quadrupole moment form factors were obtained from the cross sections, and detailed comparisons were made with theoretical predictions based on wave functions derived from nucleon-nucleon scattering experiments. Good agreement was found with a few of the wave functions used. Theoretical estimates of meson-exchange-current enhancements and relativistic effects were also compared to the data.

N−pTriple-Scattering ParameterDtat 197 MeV

The $n\ensuremath{-}p$ triple-scattering parameter ${D}_{t}$ has been measured at 197 MeV at three angles. The measurements were made by bombarding a liquid-deuterium target with polarized protons, and spin-analyzing high-energy neutrons recoiling into forward angles. Spin analysis was accomplished by a charge-exchange scattering on C${\mathrm{H}}_{2}$. The measurements are related to the ${D}_{t}$ parameter for free $n\ensuremath{-}p$ scattering through an impulse-approximation calculation which includes the $s$-wave final-state interaction between the incident proton and the proton in the deuteron. Values obtained for the free $\mathrm{np} {D}_{t}$ parameter are: +0.095\ifmmode\pm\else\textpm\fi{}0.068, -0.014\ifmmode\pm\else\textpm\fi{}0.071, and +0.058\ifmmode\pm\else\textpm\fi{}0.103 at free $n\ensuremath{-}p$ center-of-mass scattering angles of 147.4\ifmmode^\circ\else\textdegree\fi{}, and 126.9\ifmmode^\circ\else\textdegree\fi{}, respectively. These values are compared with the phase-shift solutions YLAN of Breit and collaborators, and the energy-independent solution of Arndt and MacGregor. Solutions YLAN 0, 1, 2, 2M, 3, and the Arndt-MacGregor solution do not agree with the data. Solutions YLAN 3M and 4M fit the data quite well.

Monokinetic neutron beam in the range of 50 to 150 MeV

A monokinetic neutron beam has been developed. The beam is produced by bombarding a liquid deuterium target with protons. By varying the proton energy the neutron energy is changed; energies from 50 to 150 MeV can be obtained. The neutron beam has an energy width of between 6 and 10 MeV. The main contribution to the width is the energy loss of the protons in the deuterium target. At full energy the neutron intensity is 4 × 10 4/sec. The beam greatly simplifies neutron-proton scattering experiments and also enables one to undertake nuclear spectroscopy.

Elastic Electron-Deuteron Scattering and Possible Meson-Exchange Effects

Abstract : Data on elastic electron-deuteron scattering is obtained using a two-spectrometer coincidence-detection technique. Preliminary analysis of the data has been compared with an impulse approximation theory and has enabled the investigation of possible meson-exchange and/or relativistic effects. The measurements were made using a 1.2 cm thick liquid deuterium target and two 180 degree N=1/2, double-focusing magnetic spectrometers. Deuterons were deflected by a 72-inch, 100 MeV/c spectrometer and detected by a six-channel ladder of plastic scintillators. Electrons were deflected by a 36-inch, 550 MeV/c spectrometer and detected by a similar five-channel ladder with a liquid Cerenkov backing counter. The solid angle was defined by the 36-inch spectrometer. By demanding a coincidence between counts from each spectrometer, background events from competing inelastic processes were eliminated. De3ayed accidental coincidence rates were monitored. (Author)

A low evaporation target for liquid hydrogen, deuterium or helium

A liquid hydrogen, deuterium or helium target, insulated by vacuum and low temperature radiation shields, is described. Its future is a low evaporation rate of liquid hydrogen ≈ 10 −2lt·hr −1. Deuterium is condensed by a single current heat exchange at a final pressure of about 0.4 atm using nitrogen and hydrogen as refrigerating liquids. A valve system permits to empty and fill rapidly the liquid volume exposed to γ-ray beam. Using liquid helium the evaporation reaches values less than 2 × 10 −1lt·hr −1 of liquid.

The d(p, 2p)n reaction at 50 MeV

Proton pairs from a liquid deuterium target, bombarded with 50 MeV protons, were detected by scintillation counter telescopes and the correlated energy spectra recorded on magnetic tape. Deviations from a simple theory were observed which may be interpreted as due to the breakdown of the impulse approximation in this energy region.

Liquid hydrogen and deuterium target for use with high energy accelerators

We describe the construction and operation of a liquid hydrogen and deuterium target which has proved useful in experiments with the 1 GeV electron linac of the Ecole Normale Supérieure. The essential features of the target are its relative simplicity of construction and ease of operation. In particular, the facility of filling and emptying the target appendix is provided by remote control with a switching time of about five seconds. Three successful experiments have been completed with the use of this target.

Photoproduction of Negative Pions in Deuterium

The energy spectrum at 30° and the angular distribution of protons produced in the reaction γ + d → p + p + π-were measured. A thin liquid deuterium target was irradiated by the 307 MeV bremsstrahlung beam of the Glasgow electron synchrotron. A proton was detected in coincidence with the negative pion using scintillation counter telescopes. The pions were detected at 90° ± 4° in an energy range from 46 to 60 MeV. The results are in agreement with the predictions of the spectator model and the impulse approximation.

Deuteron Compton Effect

Elastic scattering by deuterons of photons between 190 and 250 MeV has been measured by exposing a liquid deuterium target to the bremsstrahlung beam of the University of Illinois 300-MeV betatron. The scattered photons were detected by a lead glass total absorption-type \ifmmode \check{C}\else \v{C}\fi{}erenkov counter, and the recoil deuterons were momentum analyzed in a magnetic field and detected by a scintillation counter telescope. The observed cross sections in the center-of-momentum system, in Thomson proton units of ${(\frac{{e}^{2}}{{M}_{p}})}^{2}=2.35\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}$ ${\mathrm{cm}}^{2}$/sr, are, for a photon c.m. scattering angle of 140\ifmmode^\circ\else\textdegree\fi{}, 0.879\ifmmode\pm\else\textpm\fi{}0.10 at 189 MeV and 0.751\ifmmode\pm\else\textpm\fi{}0.11 at 219 MeV; and for a photon c.m. scattering angle of 110\ifmmode^\circ\else\textdegree\fi{}, 0.943\ifmmode\pm\else\textpm\fi{}0.13 at 218 MeV and 1.47\ifmmode\pm\else\textpm\fi{}0.26 at 250 MeV. These values are compared with those using the neutron and proton amplitudes predicted by dispersion relations and employing the impulse approximation, and with the exception of the point at 189 MeV are found to be consistent with the theoretical calculations.

Depolarization in 212-Mev Quasi-Elasticp−nScattering

The triple scattering parameter $D$ for 212-Mev quasi-elastic $p\ensuremath{-}n$ scattering from deuterium has been measured at c.m. angles of 40\ifmmode^\circ\else\textdegree\fi{}, 50\ifmmode^\circ\else\textdegree\fi{}, 60\ifmmode^\circ\else\textdegree\fi{}, 70\ifmmode^\circ\else\textdegree\fi{}, and 80\ifmmode^\circ\else\textdegree\fi{}. Protons and recoil neutrons from a liquid deuterium target were detected in coincidence. The experimental results are compared with the theoretical predictions of Breit and co-workers.

Elastic Scattering of 146-Mev Polarized Protons by Deuterons

The polarization and differential cross section of 146-Mev protons elastically scattered by deuterons have been measured in the center-of-mass angular range from 3.9\ifmmode^\circ\else\textdegree\fi{} to 170\ifmmode^\circ\else\textdegree\fi{}. A description of the liquid deuterium target and detection apparatus which permitted the measurement of the elastic events over these angles is given. At small angles the proton was energy analyzed; at large angles the recoil partner of the proton, the deuteron, was identified and energy analyzed. Although the energy resolution of \ifmmode\pm\else\textpm\fi{}1.7 Mev and the angular resolution of \ifmmode\pm\else\textpm\fi{}2.0\ifmmode^\circ\else\textdegree\fi{} were sufficient to separate quasi-elastic events from elastic events at most angles, they were insufficient to resolve unambiguously the 2.3-Mev inelastic events resulting from the formation of virtual deuterons. The measured cross section is in qualitative agreement with cross sections at neighboring energies; no comparison of measured polarizations is possible due to the lack of other experiments. The cross sections and polarization for angles less than 80\ifmmode^\circ\else\textdegree\fi{} c.m. are well fitted by the Kerman, McManus, and Thaler theory using the Gammel and Thaler nucleon-nucleon potential description. The energy and angular dependence of the large-angle pickup cross section proposed by Chew and Goldberger agree well with experiment; however, the small measured positive polarization is not predicted by this theory, and probably indicates destructive interference between the direct and the pickup scattering.

Photodisintegration of the Deuteron from 500 to 900 Mev

The reaction gamma + d yields p + n was studied for photon energies between 500 and 900 Mev. Bremsstrahlung from the California Institute of Technology electron synchrotron was incident on a liquid deuterium target. Measurements of the energy and angle of the protons arising in the interactions were sufficient to establish that photodisintegration without pion emission occurred and also to determine the energy of the photon which gave rise to the detected proton. An excitation curve was obtained at 90 deg in the laboratory, and angular distributions were measured for photon energies of 500 and 700 Mev. The total cross section decreased smoothly from 7 mu b at 500 Mev to 1 mu b at 900 Mev. (auth)

A thin liquid hydrogen or deuterium target

The construction and performance of a low background double-walled flat liquid hydrogen or deuterium target of precisely known thickness is described.