Precise Proton-Polarization Standards Determined with a Lamb-Shift Ion Source Incorporating a Nuclear Spin Filter

Ohlsen, G.G.; McKibben, J.L.; Lawrence, G.P.; Keaton, P.W.; Armstrong, D.D.

doi:10.1103/physrevlett.27.599

Cited by 138 publications

(9 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A nuclear spin-polarized 20 F beam was produced using a polarization transfer reaction, 19 F( − → 2 H,p) − → 20 F, with a polarized deuteron ( 2 H) beam provided by the polarized ion source (PIS) combined with a 12-UD pelletron accelerator (12 MV) at UTTAC. A polarized 2 H beam was produced using the Lamb-shift-type polarizer and a typical degree of polarization was 75% measured by the quench-ratio method [19].…”

Section: Fmentioning

confidence: 99%

See 1 more Smart Citation

Low-energy test of second-class current inβdecays of spin-aligned20F and20Na

et al. 2011

View full text Add to dashboard Cite

The G-parity-violating, second-class current-(SCC) induced tensor term in the weak-nucleon axial-vector current was determined from β-decay correlation measurements of the mass A = 20 mirror pair. The alignment correlation terms in the β-decay angular distribution from the purely spin aligned mirror pair, 20 F and 20 Na, were measured in the present study. Combining the present results with existing results of β and delayed γ -ray angular correlation measurements for the A = 20 mirror pair, the SCC-induced tensor term was extracted to be d II /Ac = 0.18 ± 0.48. In the extraction, the weak-magnetism term, b/Ac = 8.58 ± 0.28, evaluated from the M1 analog γ -ray decay strength, was used in a framework of the conserved vector current hypothesis. This is the first unambiguous extraction of the (b − d II )/Ac term free from the contribution of the second-forbidden form factor, j 2 , in the axial-vector current, which was a limiting factor for accurate determination of nonexistence of the SSC in the β decay of the A = 20 system. K. MINAMISONO et al. PHYSICAL REVIEW C 84, 055501 (2011) cancellations [5,10], possibly due to uncertainties in the nuclear structure. Therefore, the search for violation should be undertaken in various mass systems. For this purpose, β-decay correlation measurements were performed in the A = 8 (β-α angular correlation) [11,12] and A = 20 (β-γ angular correlation) [13-17] mirror systems. The β-decay correlation terms were formulated to first order of recoil terms in Ref. [7] and expressions taken in the reference will be used hereafter in this article. Unambiguous extraction of SCC from those correlation measurements, however, has been rather difficult due to imperfect knowledge of the M1/E2 mixing ratio of M1 analog γ decays and poor statistical error of the γ -ray decay strengths, from which a second-forbidden form factor, f , in the vector current is evaluated under an assumption of CVC.An alternative procedure to extract the SCC-induced tensor term was recently introduced in the A = 8 system [18], where the alignment correlation terms in the β-decay angular distribution from nuclear-spin aligned 8 Li and 8 B were combined with the β-α angular correlation terms. The (b − d II )/Ac term and other coupling constants associated with higherorder matrices are independently determined by fitting both correlation terms simultaneously. Here b/Ac is the weak magnetism, d II /Ac is the SCC-induced tensor term with c being Gamow-Teller form factor and g T /g A = d II /Ac. This procedure, combining both correlation terms, is a more reliable way to extract the (b − d II )/Ac term than that with a single correlation measurement. It is noted that the SCC-induced tensor term always appears with the weak magnetism in those correlation type measurements, and therefore, precise extraction of the SCC-induced tensor term is possible only when the weak magnetism is well known.The alignment correlation terms of the A = 20 system, 20 F(I π = 2 + , T 1/2 = 11.07 s) and 20 Na(I π = 2 + , T 1/2 = 447.9 ms), were m...

show abstract

Section: Fmentioning

confidence: 99%

“…A polarized 2 H beam was produced using the Lamb-shift-type polarizer and a typical degree of polarization was 75% measured by the quench-ratio method [19]. The polarized 2 H − ions were injected into the 12-UD pelletron accelerator and accelerated to 6 MeV.…”

Section: Fmentioning

confidence: 99%

Low-energy test of second-class current inβdecays of spin-aligned20F and20Na

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The beam intensity, -1.25xl0 6 /s, was measured to ±1% with an ionization chamber. Beam polarization was monitored to ± 1% absolute accuracy by the quench technique 6 and also with an upstream four-arm polarimeter. Target polarization was measured by standard NMR techniques with an absolute accuracy of ±4% and relative errors of ± 1%; it was checked with ±4% absolute accuracy with pp elastic scattering.…”

Section: F^ and 3 Pmentioning

confidence: 99%

Evidence against broad dibaryons

et al. 1988

View full text Add to dashboard Cite

Spin-correlation parameters ALL, ASL, ANL, ANQ, ASO, ALO, and AOL have been measured for the reaction pp -» npK + at 492, 576, 643, 729, and 796 MeV. An isobar analysis determines magnitudes and phases of partial waves up to AW l Fz. For the amplitude NNOD2)-»NACS2), the phase shows a strong threshold enhancement in the A A channel, dropping from 44.4° ±4.4° at 492 MeV to 11.9° ± 1.9 ° at 796 MeV. Other phases show little activity. Broad dibaryons are conclusively ruled out in *Z>2, 3 F3, and 3 P2 in this energy range.PACS numbers: 13.75.Cs, 14.20.PtThere has been considerable speculation on the existence of dibaryon resonances 1 in the mass range 2110 to 2250 MeV/c 2 , accessible in pp scattering with beams of 500 to 800 MeV. A recent review has been given by Locher, Sainio, and Svarc. 2 Most of the evidence comes from the AW elastic channel and AW-* nd. However, branching ratios to AW and nd are small (< 15%), and the remaining channel width can lie only in NNn, dominantly 7VA. Unambiguous identification of a resonance would therefore be a large and rapid phase increase with laboratory energy in a partial wave for NN-+NA. Prime candidates are AW l D 2 , 3 F^ and 3 P 2 .We report measurements on pp -• npn + made at the Clinton P. Anderson Meson Physics Facility with a longitudinally polarized target and a beam whose polarization was oriented successively normal (TV) to the nA production plane, sideways (S), and longitudinally (L). Observables A S L, A NL , A m , A S o, A L o, and A 0L depend on interferences and hence are phase sensitive. The parameter ALL depends on amplitudes squared, but with opposite signs for triplet and singlet initial states; it is crucial in separation of X D 2 from 3 F3 and 3 P\ amplitudes. From these observables, we determine low partial waves in both magnitude and phase.Two previous experiments along these lines have been reported. Waltham et at. measured A^o, AON, Ass, A NN , and A LL at 420, 465, and 510 MeV at TRIUMF. Present results have statistics a factor 10 better near 500 MeV. Wicklund et al A measured ANO, ^so, and A L o with high statistics at the Argonne zero-gradient synchrotron at 569, 806, 1012, and 1253 MeV. Our measurements extend significantly the number of observables and are more closely spaced in energy.First we describe the experiment briefly; details will be given in a later publication. The polarized propanediol target was 2 cm in diameter and 4 cm long. The field was provided by superconducting Helmholtz coils, leaving conical apertures upstream and downstream with 48° half angle, and an aperture of ±10.5° around 90°. All three final-state particles were detected in coincidence. The proton and n* were tracked in pairs of multiwire proportional chambers and drift chambers covering as much as possible of all three apertures in the magnet. Nucleons emerged within the downstream aperture. Pions were also detected near 90 ° and in the backward cone (down to 70 MeV/c); wide coverage of the geometry was important in the determination of amplitudes uniquely and accura...

show abstract

“…The polarization of the deuteron beam was measured by the quench-ratio method [5] about every two hours. The typical value of the beam intensity was about 100 nA, and that of the beam polarization was about 0.70.…”

Section: Pos(nic-ix)193mentioning

confidence: 99%