Fermilab 15-ft Bubble Chamber Research Articles

A measurement of the holographic minimum-observable beam branching ratio in the FERMILAB 15-ft bubble chamber

Holography has been used successfully in combination with conventional optics for the first time in a large cryogenic bubble chamber, the 15-foot bubble chamber at Fermilab, during a physics run. The innovative system combined the reference beam with the object beam, irradiating a conical volume of ∼1.4 m 3. Bubble tracks from neutrino interactions with a width of ∼120 μm have been recorded with good contrast. The ratio of intensities of the object light to the reference light striking the film is called the beam branching ratio. We obtained in our experiment an exceedingly small minimum-observable ratio of (0.54±0.21)×10 −7. The technology has the potential for a wide range of applications.

Micro-e+ dilepton production in charged-current nu micro interactions.

The production of ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ dileptons by muon neutrinos is studied in a high-statistics bubble-chamber experiment. The experiment consisted of exposing the Fermilab 15-ft bubble chamber filled with a heavy Ne-${\mathrm{H}}_{2}$ mix to a wideband neutrino beam. In a total sample of 146 700\ifmmode\pm\else\textpm\fi{}11 700 charged-current interactions, 461 events with an ${e}^{+}({P}_{{e}^{+}}>300 \mathrm{MeV}/c)$ and a ${\ensuremath{\mu}}^{\ensuremath{-}}$ are observed. The rate for ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ dilepton production in measured to be (0.42\ifmmode\pm\else\textpm\fi{}0.06)%. The energy dependence of this rate is presented. The kinematic distributions for the ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ events are consistent with charm production and subsequent semileptonic decay. A total of 60 ${K}_{S}^{0}$ and 31 ${\ensuremath{\Lambda}}^{0}$ decays were observed in the ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ event sample. The measured rates for neutral-strange-particle production are 0.78\ifmmode\pm\else\textpm\fi{}0.12 $\frac{{K}^{0}}{{\overline{K}}^{0}}'\mathrm{s}$ and 0.19\ifmmode\pm\else\textpm\fi{}0.04 ${\ensuremath{\Lambda}}^{0}'\mathrm{s}$ per ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ event. Finally, rates for ${\ensuremath{\Lambda}}_{c}^{+}$, ${D}^{0}$, and ${D}^{+}$ production in charged-current ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ interactions are derived. They are found to be (${4}_{\ensuremath{-}2}^{+10}$)%, (${1.7}_{\ensuremath{-}0.7}^{+0.5}$)%, and (${1.3}_{\ensuremath{-}0.5}^{+0.4}$)%, respectively.

Nu micro- nu e universality in charged-current neutrino interactions.

A total of $1403{\ensuremath{\nu}}_{e}$ and $179{\overline{\ensuremath{\nu}}}_{e}$ charged-current interactions with energies ranging up to 200 GeV were observed in a wideband neutrino-beam experiment using the Fermilab 15-ft bubble chamber filled with a heavy Ne-${\mathrm{H}}_{2}$ mix. As a test of ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{-}{\ensuremath{\nu}}_{e}$ universality, these events were compared to samples of ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ charged-current events obtained during the same experiment. The ${\ensuremath{\nu}}_{e}\ensuremath{-}\mathrm{to}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ cross-section ratio was measured to be 1.09\ifmmode\pm\else\textpm\fi{}0.17, and the corresponding ratio for antineutrinos was 1.46\ifmmode\pm\else\textpm\fi{}0.34. Kinematic distributions and charged-particle multiplicities were also consistent with universality. The neutral-strange-particle production rate was measured to be (11.7\ifmmode\pm\else\textpm\fi{}1.2)% for ${\ensuremath{\nu}}_{e}$ and (5.2\ifmmode\pm\else\textpm\fi{}2.2)% for ${\overline{\ensuremath{\nu}}}_{e}$, in good agreement with the ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ rates. The relative rate for ${e}^{\ensuremath{-}}{e}^{+}$ dilepton production by ${\ensuremath{\nu}}_{e}$ was (0.82\ifmmode\pm\else\textpm\fi{}0.47)%, also consistent with universality. The rate for neutral-strange-particle production in ${e}^{\ensuremath{-}}{e}^{+}$ dilepton events is reported for the first time. The measured rate of 0.64\ifmmode\pm\else\textpm\fi{}0.45 agrees with the value expected from universality.

Dimuon production by neutrinos in the Fermilab 15-ft bubble chamber at the Tevatron.

The Fermilab 15-ft bubble chamber has been exposed to a quadrupole triplet neutrino beam produced at the Tevatron. The ratio of {nu} to {bar {nu}} in the beam is approximately 2.5. The mean event energy for {nu}-induced charged-current events is 150 GeV, and for {bar {nu}}-induced charged-current events it is 110 GeV. A total of 64 dimuon candidates (1 {mu}{sup +}{mu}{sup +}, 52 {mu}{sup {minus}}{mu}{sup +} and {mu}{sup +}{mu}{sup {minus}}, and 11 {mu}{sup {minus}}{mu}{sup {minus}}) is observed in the data sample of approximately 13 300 charged-current events. The number and properties of the {mu}{sup {minus}}{mu}{sup {minus}} and {mu}{sup +}{mu}{sup +} candidates are consistent with their being produced by background processes, the important sources being {pi} and {ital K} decay and punchthrough. The 90%-C.L. upper limit for {mu}{sup {minus}}{mu}{sup {minus}}/{mu}{sup {minus}} for muon momenta above 4 GeV/{ital c} is 1.2{times}10{sup {minus}3}, and for momenta above 9 GeV/{ital c} this limit is 1.1{times}10{sup {minus}3}. The opposite-sign-dimuon--to--single-muon ratio is (0.62{plus minus}0.13)% for muon momenta above 4 GeV/{ital c}. There are eight neutral strange particles in the opposite-sign sample, leading to a rate per dimuon event of 0.65{plus minus}0.29. The opposite-sign-dimuon sample is consistent with the hypothesis of charm production and decay.

Coherent production of pi + and pi - mesons by charged-current interactions of neutrinos and antineutrinos on neon nuclei at the Fermilab Tevatron.

Coherent single-pion production on neon nuclei is studied using the Fermilab 15-ft bubble chamber filled with a heavy Ne-H{sub 2} mixture and exposed to the Tevatron neutrino beam. In the neutrino energy range 40--300 GeV, the net signal is 20{plus minus}6 events, giving a corrected rate per charged-current event of (0.26{plus minus}0.10)%. The cross section and kinematic distributions agree with the predictions of a model based on partial conservation of axial-vector current and meson dominance.

Evidence for coherent neutral-pion production by high-energy neutrinos.

We have observed a signal of 55 isolated $\ensuremath{\gamma}$-conversion pairs produced in a wide-band neutrino beam using the Fermilab 15-ft bubble chamber filled with a heavy Ne-${\mathrm{H}}_{2}$ mixture. The signal is consistent with coherent neutral-current single-${\ensuremath{\pi}}^{0}$ production followed by decay of the ${\ensuremath{\pi}}^{0}$ with one of the decay $\ensuremath{\gamma}'\mathrm{s}$ being lost. This signal corresponds to a rate of (2.0 \ifmmode\pm\else\textpm\fi{} 0.4) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$ of the total ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ charged-current cross section at our average ${E}_{\ensuremath{\nu}}$ of 20 GeV. From this result, we obtain a value of $\ensuremath{\beta}=0.98\ifmmode\pm\else\textpm\fi{}0.24$ for the weak-neutral-current isovector axial-vector coupling.

Pulse stretching in a Q-switched ruby laser for bubble chamber holography

In testing a holgraphic particle track recording system for the Fermilab 15-ft bubble chamber, it was shown that the peak power of Q-switched laser pulses (~50-ns duration) at the required energy gave rise to boiling during the chamber expansion. A pulse stretching technique is described which was developed to reduce the peak power. Applied to a ruby laser (oscillator and three amplifiers) with a maximum Q-switched output of 30 J, pulses of up to 100-μs duration with coherence up to and exceeding 11 m at 2.5 μs were produced. These pulses were amplified to ~5 J without shape degradation. The considerably increased coherence length will find applications in many fields of pulsed holography, and its use with fiber optics is particularity promising.

Strange-particle production in neutrino-neon charged-current interactions.

We report a study of strange-particle production from 61?0 charged-current ${\ensuremath{\nu}}_{\ensuremath{\mu}}$Ne interactions in the Fermilab 15-ft bubble chamber. The observed sample consists of 2279 ${K}^{0}$, 1843 \ensuremath{\Lambda} (including 94 ${\ensuremath{\Sigma}}^{0}$), 93 \ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{}, and 4 ${\ensuremath{\Xi}}^{\mathrm{\ensuremath{-}}}$. We give inclusive production rates for each of these, as well as the rates for specific single-, double-, and triple-vee channels. From these we derive the rates for associated production of ss\ifmmode\bar\else\textasciimacron\fi{} quark pairs, and for single-s-quark production via charm decay. The dependence of ${K}^{0}$ and \ensuremath{\Lambda} production on ${E}_{\ensuremath{\nu}}$, ${Q}^{2}$, ${W}^{2}$, ${x}_{B}$, and ${y}_{B}$ are given. Normalized distributions of Feynman x, rapidity, fragmentation variable z, and transverse momentum squared are obtained for ${K}^{0}$ and \ensuremath{\Lambda}, and compared with those for charged pions. QCD predictions on the behavior of 〈${P}_{T}$${\mathrm{}}^{2}$〉 are tested.

Opposite-sign dilepton production in nu micro interactions.

We report on a high-statistics bubble-chamber experiment using the Fermilab 15-ft bubble chamber filled with a heavy neon/hydrogen mixture exposed to a wide-band neutrino beam. In a sample of 106 000 ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ >0.3 GeV/c) and a negative muon were observed. After corrections, the rate for opposite-sign dilepton production for ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ charged-current events is (0.52\ifmmode\pm\else\textpm\fi{}0.09)%. The ${E}_{\ensuremath{\nu}}$ dependence of this rate from threshold to \ensuremath{\approxeq}200 GeV is presented. The kinematic distributions and strange-particle content of the dilepton events are consistent with those expected from charm-particle production in neutrino interactions. A total of 58 neutral strange particles (\ensuremath{\Lambda}\ensuremath{\rightarrow}p${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, ${K}_{S}^{0}$\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$) are observed in these events, where less than 16 are expected from conventional charged-current interactions. The presence of a significant excess of \ensuremath{\Lambda}'s is evidence for substantial charmed-baryon production.

Search for high-energy tau-neutrino interactions

Kinematic selection criteria are developed for separating tau-neutrino charged-current interactions from a large background of muon- and electron-neutrino interactions. The criteria are designed to detect the three-prong decay mode of the $\ensuremath{\tau}$ lepton and rely on the three-particle combination's transverse momentum being anticorrelated with the tr\'ansverse momentum of the other visible particles and being correlated with the missing transverse momentum. The criteria are applied to a sample of events from an exposure of the Fermilab 15-ft bubble chamber to the quadrupole triplet neutrino beam. The average event energies for this beam are 90 GeV for neutrino and 60 GeV for antineutrino events. The $14 \ensuremath{\tau}$ candidates selected agree with the calculated background of 14.3\ifmmode\pm\else\textpm\fi{}1.2. An upper limit on the probability of muon neutrinos oscillating into tau neutrinos of 0.053 is obtained.

Measurement of the BjorkenxandyDistributions in Neutral- and Charged-CurrentνμInteractions

Distributions of the Bjorken scaling variables x and y, and the structure function F/sub +/(x), are presented both for neutral-current and for charged-current ..nu../sub ..mu../ interactions. The data were obtained by use of the Fermilab 15-ft neon bubble chamber exposed to a narrow-band ..nu../sub ..mu../ beam. Results are based on 151 neutral-current and 683 charged-current events. An important feature of the neutral-current analysis is the event-by-event reconstruction of the outgoing neutrino.

Limits on the neutrino oscillationsν¯μ→ν¯eandν¯μ→ν¯τusing a narrow-band beam

In an exposure of the Fermilab 15-ft bubble chamber to the dichromatic antineutrino beam, 427 ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ charged-current interactions were obtained. Taking advantage of the small and well understood background flux of ${\overline{\ensuremath{\nu}}}_{e}'\mathrm{s}$ in the dichromatic ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ beam, upper limits on the rates of antineutrino oscillations are obtained, with the precision limited by statistical rather than systematic errors, in contrast to previous experiments. The 90%-C.L. upper limits obtained for the average oscillation probabilities indicated are $P({\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{e})<6.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $P({\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}})<4.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$. The mean value of the distance from the neutrino-production point to the bubble chamber divided by the neutrino energy, $〈\frac{l}{E}〉$, is 0.03 m/MeV.

On the measurement of the momentum of 19 GeV/ c electrons in a heavy liquid bubble chamber

The Fermilab 15-ft bubble chamber was exposed to an electron beam of 19 GeV/ c momentum. The chamber was filled with a heavy neon-hydrogen mixture (64% atomic Ne, 36% atomic H) and operated with a magnetic field of 3 T. The momentum of the electrons was determined from the bubble chamber pictures using two methods: (a) the measurement of the curvature of the electrons and their shower products, and (b) the measurement of the total track length of the electron and its shower. The momentum, as determined from curvature measurement of the primary electron and the e +e − pairs from the radiated gammas was 19.1±7.6 GeV/c.

Neutrino Flux and Total Charged-Current Cross Sections in High-Energy Neutrino-Deuterium Interactions

From 12 000 charged-current ..nu../sub ..mu../D events obtained in an exposure of the Fermilab 15-ft bubble chamber to a high-energy wide-band neutrino beam, the absolute neutrino flux is determined using the reaction ..nu../sub ..mu../n..--> mu../sup -/p. For the total charged-current cross section, sigma/sub t/ = kE/sub ..nu../, k = (0.68 +- 0.04 +- 0.10) x 10/sup -38/ cm/sup 2//GeV is obtained for E/sub ..nu../ between 10 and 200 GeV. No clear energy dependence of the slope parameter k is observed.

New Decay Mode of the Charmed Baryon,Λc+→Σ0π+

In a sample of approximately 17 500 charged current neutrino-deuterium interactions from an exposure of the Fermilab 15-ft bubble chamber to a high-energy wide band neutrino beam, the charmed baryon ..lambda../sup +//sub c/ is observed in a new decay mode, ..lambda../sup +//sub c/..--> sigma../sup 0/..pi../sup +/. The branching ratio times production rate is estimated to be (3.2 +- 2.1) x 10/sup -3/ for this ..sigma../sup 0/..pi../sup +/ channel.

Inclusiveπ0production in 250-GeV/cπ−pinteractions

Neutral-pion production in 250-GeV/c ${\ensuremath{\pi}}^{\ensuremath{-}}p$ interactions are studied using the Fermilab 15-ft bubble chamber. The mean number of neutral pions produced is 3.54\ifmmode\pm\else\textpm\fi{}0.15 per inelastic collision and a fit to a linear dependence on the charged multiplicity gives $〈{n}_{0}〉=1.30+0.56{n}_{\ensuremath{-}}$. The ${\ensuremath{\pi}}^{0}$ transverse- and longitudinal-momentum distributions are obtained from the inclusive $\ensuremath{\gamma}$-ray data and compared with the distribution obtained from those ${\ensuremath{\pi}}^{0}$'s which have both decay $\ensuremath{\gamma}$ rays converting in the bubble chamber.

Evidence for Hard-Gluon Bremsstrahlung in a Deep-Inelastic Neutrino Scattering Experiment

Data from νN interactions in the Fermilab 15-ft bubble chamber show that the mean transverse momentum (pT) of forward hadrons in the hadron c.m. system exceeds that of backward hadrons for W2>100 GeV2. Events with high πF, a measure of forward pT, tend to have planar hadron systems and show a three-jet structure in their angular energy flow; their number exceeds that expected in two-jet models. These observations are consistent with quantum chromodynamic predictions of hard-gluon bremsstrahlung.Received 1 June 1981DOI:https://doi.org/10.1103/PhysRevLett.47.556©1981 American Physical Society

250-GeV/cπ−pmultiplicity distributions and the two-component model

The charged-particle multiplicity distribution from 250-GeV/c ${\ensuremath{\pi}}^{\ensuremath{-}}p$ interactions in the Fermilab 15-ft bubble chamber is presented. The corrections to the raw data are described. Fits to these data along with other high-energy bubble-chamber data show that cluster models with two components---a low-multiplicity, diffractive component and a high-multiplicity, nondiffractive component---describe the data fairly well. The charged multiplicity of each cluster is found to be \ensuremath{\sim}2, while the number of clusters for each component grows linearly with $\mathrm{ln}(s)$. The multiplicity moments are consistent with other experiments. We find $〈{n}_{c}〉=8.427\ifmmode\pm\else\textpm\fi{}0.059$, ${f}_{2}^{\mathrm{cc}}=8.66\ifmmode\pm\else\textpm\fi{}0.11$, $\frac{〈{n}_{c}〉}{D}=2.038\ifmmode\pm\else\textpm\fi{}0.023$. The total inelastic cross section is ${\ensuremath{\sigma}}_{I}=21.42\ifmmode\pm\else\textpm\fi{}0.50$ mb.

Comparison ofνnandνpCharged-Current Cross Sections from High-Energy Neutrino Interactions in Deuterium

From an analysis of the reaction ${\ensuremath{\nu}}_{\ensuremath{\mu}}+d\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}+X$, obtained from an exposure of the Fermilab 15-ft deuterium-filled bubble chamber, the ratios of charged-current cross sections for ${E}_{\ensuremath{\nu}}g10$ GeV are determined to be $\frac{\ensuremath{\sigma}(\ensuremath{\nu}n)}{\ensuremath{\sigma}(\ensuremath{\nu}p)}=2.03\ifmmode\pm\else\textpm\fi{}0.28$ for $〈{E}_{\ensuremath{\nu}}〉=50$ GeV, and $\frac{\ensuremath{\sigma}(\overline{\ensuremath{\nu}}n)}{\ensuremath{\sigma}(\overline{\ensuremath{\nu}}p)}=0.51\ifmmode\pm\else\textpm\fi{}0.16$ for $〈{E}_{\overline{\ensuremath{\nu}}}〉=40$ GeV. Bjorken-$x$ distributions for neutron and proton targets show that the majority quark in the nucleon has a broader momentum distribution in the infinite momentum frame than does the minority quark.

Charmed-Baryon Production in High-Energy Neutrino-Deuterium Interactions

In a sample of approx.15 000 charged current ..nu..+d interactions from an exposure of the Fermilab 15-ft bubble chamber to a high-energy, wide-band neutrino beam, the production of the ..lambda../sub c/ /sup +/ charmed baryon decaying into ..lambda pi../sup +/ and K/sup 0/p is observed. The measured mass value is 2.275 +- 0.010 GeV. The products of the production rate and the branching ratio for these channels are (1.8 +- 0.9) x 10/sup -3/ and (3.5 +- 2.0) x 10/sup -3/, respectively.