arXiv subjects

A. A. Poblaguev

Publications and source records attributed to A. A. Poblaguev.

At least 19 recordsLinked to original sources

arXiv2026

Evaluation of the beam-induced depolarization of the HJET target at the EIC

The Polarized Atomic Hydrogen Gas Jet Target (HJET) has played a central role in the absolute calibration of proton beam polarization at RHIC and is foreseen as a key component of the hadron polarimetry program at the future Electron--Ion Collider (EIC). The substantially higher beam current, reduced bunch spacing, and shorter bunch length planned for EIC operation motivate a careful reassessment of possible beam-induced depolarization of the jet target. In this paper, the depolarization of ground-state hydrogen atoms caused by the time-dependent magnetic field of the circulating polarized proton beam is quantitatively evaluated. The hydrogen atom is treated as a four-level hyperfine system in a holding magnetic field, and transitions driven by harmonic components of the bunch-induced magnetic field are analyzed using time-dependent quantum-mechanical evolution along atomic trajectories. Numerical tracking of hydrogen atoms through the beam region is performed using nominal EIC beam parameters. It is shown that, for a holding field of $120 \mathrm{mT}$ (as used at RHIC), the resulting depolarization of the jet target at the EIC is negligibly small, $\lesssim 0.01\%$, and well below the level relevant for EIC polarization accuracy requirements. The stability of this result with respect to plausible variations of the EIC proton beam parameters is also evaluated. In addition, possible effects under alternative experimental conditions are also examined.

physics.ins-det↗

arXiv2023

Optically Pumped Polarized $^3$He$^{++}$ Ion Source Development for RHIC/EIC

The proposed polarized $^3$He$^{++}$ acceleration in RHIC and the future Electron-Ion Collider will require about $2\times10^{11}$ ions in the source pulse. A new technique had been proposed for production of high intensity polarized $^3$He$^{++}$ ion beams. It is based on ionization and accumulation of the $^3$He gas (polarized by metastability-exchange optical pumping and in the 5 T high magnetic field) in the existing Electron Beam Ion Source (EBIS). A novel $^3$He cryogenic purification and storage technique was developed to provide the required gas purity. An original gas refill and polarized $^3$He gas injection to the EBIS long drift tubes, (which serves as the storage cell) were developed to ensure polarization preservation. An infrared laser system for optical pumping and polarization measurements in the high 3--5 T field has been developed. The $^3$He polarization 80--85\% (and sufficiently long $\sim30$ min relaxation time) was obtained in the \lq\lq{open}\rq\rq\ cell configuration with refilling valve tube inlet and isolation valve closed. The development of the spin-rotator and $^3$He $^4$He absolute nuclear polarimeter at 6 MeV $^3$He$^{++}$ beam energy is also presented.

physics.ins-det↗

arXiv2023

Improved Analysis of the Breakup Corrections to the High Energy $^3$He Beam Polarization measurements with HJET

The requirements for hadron polarimetry at the future Electron Ion Collider (EIC) include measurements of the absolute helion ($^3$He, $h$) beam polarization with systematic uncertainties better than $σ^\text{syst}_P/P\le1\%$. Recently, it was suggested to utilize the Polarized Atomic Hydrogen Gas Jet Target (HJET) for precision measurement of the polarization of the $\sim$100 GeV/n helion beam. At the Relativistic Heavy Ion Collider, HJET serves to determine absolute proton beam polarization with low systematic uncertainties of about $δ^\text{syst}P/P\lesssim0.5\%$. To adapt the HJET method for the EIC helion beam, the experimentally determined ratio of the beam and target (jet) spin correlated asymmetries should be adjusted by the ratio of $p^\uparrow{h}$ and $h^\uparrow{p}$ analyzing powers $A_\text{N}^{ph}(t)/A_\text{N}^{hp}(t)$ which, in the leading order approximation, is predefined by magnetic moments of the proton and helion, $(μ_p-1)/(μ_h/2-1/3)$. However, to achieve the required accuracy in the measured polarization, the corrections due to hadronic spin-flip amplitudes and due to possible beam $^3$He breakup should be considered. Here a more accurate analysis of the possible breakup corrections to the measured $^3$He beam polarization is provided. The results confirm that the breakup corrections are negligible for the EIC helion beam absolute polarization measurement by HJET.

hep-ph↗

arXiv2022

Precision small scattering angle measurements of proton-proton and proton-nucleus analyzing powers at the RHIC hydrogen jet polarimeter

At RHIC, the hydrogen jet target polarimeter (HJET) is used to measure proton beam polarization with accuracy $σ_P^\text{syst}/P\lesssim0.5\%$ by counting low energy (1--10 MeV) recoil protons in left-right symmetric detectors. The HJET performance also allowed us to precisely measure $pp$ and $p$A (where A is any ion stored at RHIC) analyzing powers in the CNI region. The results of the measurements are discussed.

hep-ex↗

arXiv2022

On the possibility of measuring the polarization of a ${}^3\rm{He}$ beam at EIC by the HJET polarimeter

The requirements for hadron polarimetry at the future Electron Ion Collider (EIC) include measurements of the absolute helion (${}^3\text{He}$, $h$) beam polarization with systematic uncertainties better than $σ^\text{syst}_P/P\lesssim1\%$. Here, we consider a possibility to utilize the Polarized Atomic Hydrogen Gas Jet Target (HJET) for precision measurement of polarization of the $\sim$100 GeV/n helion beam. HJET, which serves to determine absolute proton beam polarization at the Relativistic Heavy Ion Collider, provides the accuracy of about $δ^\text{syst}P/P\sim0.5\%$. Potential problems for adapting the HJET method for the EIC helion beam include (i) necessity to know the ratio of $p^\uparrow{h}$ and $h^\uparrow{p}$ analyzing powers $A_\text{N}^{ph}(t)/A_\text{N}^{hp}(t)$ with high precision, ({ii) possible beam ${}^3\text{He}$ breakup, and (iii) operation in a 10 ns bunch spacing beam. Preliminary results of an analysis discussed here indicate that the listed problems can be overcome and the helion beam absolute polarization can be measured by HJET with the required accuracy.

hep-ph↗

arXiv2022

Feasibility study for precisely measuring the EIC ${}^3$He beam polarization with the Polarized Atomic Hydrogen Gas Jet Target polarimeter at RHIC

The Polarized Atomic Hydrogen Gas Jet Target polarimeter (HJET) is used to measure the absolute proton beam polarization, $σ_P^\text{syst}/P\!\lesssim\!0.5\%$, at the Relativistic Heavy Ion Collider. Here I consider the possibility of employing HJET to measure the ${}^3\text{He}$ ($h$) beam polarization at the Electron-Ion Collider (EIC). The dominant contribution to the ratio of the $h^\uparrow{p}$ and $p^\uparrow{h}$ analyzing powers, which is needed for such measurements, can be easily calculated using well-known values of the proton and helion magnetic moments, but some corrections should be applied to achieve the required accuracy. It was found that corrections due to absorption and ${}^3\text{He}$ breakup effectively cancel in the ratio and a correction due to hadronic spin-flip amplitudes can be derived from the proton beam measurements. As a result, the anticipated systematic uncertainty in the measured ${}^3\text{He}$ beam polarization can satisfy the EIC requirement $σ_P^\text{syst}/P\!\lesssim\!1\%$.

hep-ph↗

arXiv2022

Breakup corrections to the ${}^3$He beam polarization measurements at the future BNL Electron Ion Collider

Requirements for hadron polarimetry at the future Electron-Ion Collider (EIC) include measurements of absolute ${}^3\text{He} (h)$ beam polarization with systematic uncertainties better than $σ^\text{syst}_P/P\lesssim1\%$. Due to the successful use, since 2005, of the polarized hydrogen jet target polarimeter (HJET) to measure proton beam polarization at the Relativistic Heavy Ion Collider (RHIC), the HJET technique promises to be suitable for the ${}^3\text{He}$ polarimetry at EIC. For that, however, one needs to know the ratio of the $h^\uparrow{p}$ and $p^\uparrow{h}$ analyzing powers. For elastic scattering, this ratio can be evaluated with sufficient accuracy if $p^\uparrow{p}$ analyzing power is precisely known. In this paper, the deuteron beam data acquired at HJET in RHIC Run 16 was used to evaluate corrections to the measured helion beam polarization due to the ${}^3\text{He}$ breakup. The breakup effect was found to be negligible if the ratio of the beam and target (jet) single spin asymmetries are concurrently measured to determine the ${}^3\text{He}$ beam polarization.

hep-ph↗

arXiv2022

Coulomb phase corrections to the transverse analyzing power $A_N(t)$ in high energy forward proton-proton scattering

Study of polarized proton-proton elastic scattering in the Coulomb-nuclear interference region allows one to measure the forward hadronic single spin-flip amplitude including its phase. However, in a precision experimental data analysis, a phase shift correction $δ_C$ due to the long distance Coulomb interaction should be taken into account. For unpolarized scattering, $δ_C$ is commonly considered as well established. Here, we evaluate the Coulomb phase shifts for the forward elastic proton-proton single spin-flip electromagnetic and hadronic amplitudes. Only a small discrepancy between the spin-flip and non-flip phases was found which can be neglected in the high energy forward elastic $\mathit{pp}$ studies involving transverse spin. Nonetheless, the effective alteration of the hadronic spin-flip amplitude by the long distance electromagnetic corrections can be essential for interpretation of the experimental results.

hep-ph↗

arXiv2020

Systematic error analysis in the absolute hydrogen gas jet polarimeter at RHIC

The Polarized Atomic Hydrogen Gas Jet Target polarimeter (HJET) is operated at the Relativistic Heavy Ion Collider (RHIC) since 2004 to measure the absolute polarization of each colliding proton beam. Polarimeter detectors and data acquisition were upgraded in 2015 to increase the solid angle, energy range, and to improve the energy and time resolution. These upgrades along with an improved beam intensity and polarization allowed us to greatly reduce the statistical and systematic errors for the proton polarization measurements in RHIC Runs 15 ($E_\text{beam}\!=\!100~\text{GeV}$) and 17 ($255~\text{GeV}$). For a typical 8 hour RHIC store, the measured proton beam average polarization was about $P_\text{beam}\!\sim\!55\pm2.0_\text{stat}\pm0.3_\text{syst}\%$. The elastic $\mathit{pp}$ analyzing power, $A_\text{N}(t)\!\sim\!0.04$, was determined with a precision of about $|δA_\text{N}(t)|\!\sim\!0.0002$ in the momentum transfer squared range $0.001\!<\!-t\!<\!0.020\,\text{GeV}^2$. In this paper we present a detailed systematic error analysis of the polarization measurements at HJET. Perspectives of using the HJET based absolute polarimeters in the future Electron Ion Collider (EIC) will be also discussed.

physics.ins-det↗

arXiv2019

Corrections to the Elastic Proton-Proton Analyzing Power Parametrization at High Energies

The HJET Polarized Atomic Hydrogen Gas Jet Target polarimeter (HJET) polarimeter was designed to measure the absolute polarization of the proton beams at the Relativistic Heavy Ion Collider. In these measurements, the small scattering angle elastic $pp$ single $A_N(t)$ and double $A_{NN}(t)$ spin analyzing powers can be precisely determined. The experimental accuracy achieved at HJET requires corrections to the $A_N(t)$ parametrization, conventionally used for such studies. In this paper we evaluate the corrections to the analyzing powers due to (i) the differences between the electromagnetic and hadronic form factors and (ii) the $m_p^2/s$ terms in the elastic spin-flip $pp$ electromagnetic amplitude. The corresponding alterations of the evaluated hadronic spin-flip amplitudes are about the same as the experimental uncertainties of the HJET measurements. The proposed corrections may have implications for the elastic $pp$ forward real-to-imaginary amplitude ratios $ρ$ determined in unpolarized $pp$ experiments.

hep-ph↗

arXiv2019

Precision Small Scattering Angle Measurements of Elastic Proton-Proton Single and Double Spin Analyzing Powers at the RHIC Hydrogen Jet Polarimeter

The Polarized Atomic Hydrogen Gas Jet Target polarimeter is employed by the Relativistic Heavy Ion Collider (RHIC) to measure the absolute polarization of each colliding proton beam. Polarimeter detectors and data acquisition were upgraded in 2015 to increase solid angle, energy range and energy resolution. These upgrades and advanced systematic error analysis along with improved beam intensity and polarization in RHIC runs 2015 ($E_\textrm{beam}=100\,\text{GeV}$) and 2017 ($255\,\text{GeV}$) allowed us to greatly reduce the statistical and systematic uncertainties for elastic spin asymmetries, $A_N(t)$ and $A_NN(t)$, in the Coulomb-nuclear interference momentum transfer range $0.0013<-t<0.018\,\text{GeV}^2$. For the first time hadronic single spin-flip $r_5$ and double spin-flip $r_2$ amplitude parameters were reliably isolated at these energies and momentum transfers. Measurements at two beam energies enable a separation of Pomeron and Regge pole contributions to $r_5(s)$ and $r_2(s)$, indicating that the spin component may persist at high energies.

hep-ex↗

arXiv2007

An Improved Shashlyk Calorimeter

Shashlyk electromagnetic calorimeter modules with an energy resolution of about 3%/sqrt{E (GeV)} for 50-1000 MeV photons has been developed, and a prototype tested. Details of these improved modules, including mechanical construction, selection of wave shifting fibers and photo-detectors, and development of a new scintillator with improved optical and mechanical properties are described. How the modules will perform in a large calorimeter was determined from prototype measurements. The experimentally determined characteristics of the calorimeter prototype show energy resolution of sigma_E/E=(1.96+-0.1)% \oplus (2.74+-0.05)%/sqrt{E}, time resolution of sigma_T = (72+-4)/sqrt{E} \oplus (14+-2)/E (ps), where photon energy E is given in GeV units and \oplus means a quadratic summation. A punch-through inefficiency of photon detection was measured to be ε= 5*10^{-5} (Θ>5 mrad).

physics.ins-det↗

arXiv2006

First observation of the decay K+ -> e+ nu mu+ mu-

Experiment 865 at the Brookhaven AGS has observed the decay K^+ -> e^+ nu mu^+ mu^-. The branching ratio extracted is (1.72 +/- 0.37(stat) +/- 0.17(syst) +/- 0.19(model)) x 10^{-8} where the third term in the error results from the use of a model to extrapolate into a kinematic region dominated by background.

hep-ex↗

arXiv2005

An Improved upper limit on the decay K^+ -> pi^+ mu^+ e^-

Based on results of a search for the lepton-family-number-violating decay $K^+ \to π^+μ^+ e^-$ with data collected by experiment E865 at the Alternating Gradient Synchrotron of Brookhaven National Laboratory, we place an upper limit on the branching ratio at $2.1 \times 10^{-11}$ (90% C.L.). Combining the results with earlier E865 data and those of a previous experiment, E777, an upper limit on the branching ratio of $1.3 \times 10^{-11}$ (90% C.L.) is obtained.

hep-ex↗

arXiv2004

New, high statistics measurement of the K+ -> pi0 e+ nu (Ke3) branching ratio

E865 at the Brookhaven National Laboratory AGS collected about 70,000 K+(e3) events with the purpose of measuring the relative K+(e3) branching ratio. The pi0 in all the decays was detected using the e+e- pair from pi0 -> e+e-gamma decay and no photons were required. Using the Particle Data Group branching ratios for the normalization decays we obtain BR(K+(e3(gamma))=(5.13+/-0.02(stat)+/-0.09(sys)+/-0.04(norm))%, where $K+(e3(gamma)) includes the effect of virtual and real photons. This result is 2.3 sigma higher than the current Particle Data Group value. The implications of this result for the $V_{us}$ element of the CKM matrix, and the matrix's unitarity are discussed.

hep-ex↗

arXiv2004

K+ -> pi0 e+ nu branching ratio from E865

E865 at the Brookhaven National Laboratory AGS collected about 70,000 K+(e3) events to measure the K+(e3) branching ratio relative to the observed K+ -> pi+ pi0, K+ -> pi0 mu+ nu, and K+ -> pi+ pi0 decays. The pi0 in all the decays was detected using the e+e- pair from pi0 -> e+e-gamma decay and no photons were required. Using the Particle Data Group branching ratios for the normalization decays we obtain BR(K+(e3(gamma))=(5.13+/-0.02(stat)+/-0.09(sys)+/-0.04(norm))%, where $K+(e3(gamma)) includes the effect of virtual and real photons. This result is 2.3 sigma higher than the current Particle Data Group value. The implications of this result for the $V_{us}$ element of the CKM matrix, and the matrix's unitarity are discussed.

hep-ex↗

arXiv2003

Development of Shashlyk Calorimeter for KOPIO

A Shashlyk calorimeter prototype for the KOPIO experiment has been constructed and experimentally tested. The energy resolution of about 4%/sqrt(E(GeV)) for 0.5-2.0 GeV/c positrons was obtained. Based on this results as well as on the results of special measurements, a Monte-Carlo model of the Shashlyk module response was developed. This model, including the effects of shower evolution, light collection in scintillator plates, light attenuation in fibers, quantum efficiency of the photodetector, thresholds and noises in the readout system is consistent with experimental results. Possible improvment of the Shashlyk energy resolution up to 3%/sqrt(E(GeV)), the level required by KOPIO experiment, are discussed.

physics.ins-det↗

arXiv2003

On the analysis of the pi -> e nu gamma experimental data

The most general amplitude for the radiative pion decay pi -> e nu gamma including terms beyond V-A theory is considered. The experimental constraints on the decay amplitude components are discussed. A model independent presentation of the results of high statistics and high resolution experiments is suggested.

hep-ph↗