Journals published by the American Physical Society can be found at http://publish.aps.org/We have measured the spin-transfer parameters K(LL), K(SL), K(LS) and K(SS) at 635 MeV from 50-degrees to 178-degrees c.m. and at 485 MeV from 74-degrees to 176-degrees c.m. These new data have a significant impact on the phase-shift analyses. There are now sufficient data near these energies to overdetermine the elastic nucleon-nucleon amplitudes

Adams, D. L.

Ambrose, DA

Coffey, P.

Glass, G.

Hiebert, John C.

Jeppersen, R. H.

Johnston, K.

Koch, K.

McNaughton, K. H.

McNaughton, M. W.

Mercer, D. J.

Northcliffe, L. C.

Riley, P. J.

Simon, A. J.

Spinka, H.

Supek, I.

Tanaka, N.

Tripard, G. E.

Woolverton, H.

Texas A&amp;M Repository

PHYSICAL REVIEW C VOLUME 46, NUMBER 1 JULY 1992ARTICLESnp elastic spin-transfer measurements at 485 and 635 MeVK. H. McNaughton, D. A. Ambrose, P. Coffey, K. 3ohnston, ' and P. J. RileyUniversity of Texas, Austin, Texas 78719M. W. McNaughton, K. Koch, t I. Supek, and N. Tanaka~Los Alamos National Laboratory, Los Alamos, Nenes Mexico 87$$$G. Glass, J. C. Hiebert, L. C. Northcliffe, and A. J. SimonTexas ASM Universa ty, C'ollege Station, Texas 778/8D. J. MercerUniversity of Colorado, Boulder, Colorado 80808D. L. AdamsRice University, Houston, Texas 77251H. SpinkaArgonne National Laboratory, Argonne, Illinois 80/89R. H. JeppesenUniversity of Montana, Missoula, Montana $9818G. E. TripardWashington State University, Pullman, Washington 99I8$H. WoolvertonUniversity of Central Arkansas, Con+ay, Arkansas 780M(Received 27 March 1992)We have measured the spin-transfer parameters E~I., E~l. , Al. p, and Egg at 635 MeV from 50'to 178' c.m. and at 485 MeV from 74' to 176' c.m. These new data have a significant impact on thephase-shift analyses. There are now sufticient data near these energies to overdetermine the elasticnucleon-nucleon amplitudes.PACS number(s): 21.30.+y, 13.75.Cs, 24.70.+sI. INTRODUCTIONThe 1991 status of the np elastic phase-shift analy-sis near 650 MeV was summarized by Bugg and Bryan[1] as follows. "There are not enough accurate spin-dependent data to give a secure solution and most ofthe phase shifts are strongly correlated, with correlation'Current Address: Los Alamos National Laboratory, LosAlamos, NM 87545.t Current Address: PSI, LG I25, CH 5232 Villigen PSI,Switzerland.~ Deceased.coefficients as high as 76%." "To stabilize the solution,Wolfenstein (spin-transfer) parameter data are requiredof similar quality to those at 800 MeV. " We present thesenew data here. With the inclusion of these data, Buggreports stable solutions with small correlations at 650MeV.Previous spin-dependent data near 650 MeV includethe analyzing power [2], the four spin-correlation parame-ters [3—6], and the four spin-transfer parameters reportedhere. These data are sufhcient to over determine the elas-tic nucleon-nucleon amplitudes [7].Previous measurements of the spin-transfer param-eters are discussed in Sec. IV. The normalization ofboth present and previous LAMPF data is discussed inSec. III.46 47 1992 The American Physical Society48 K. H. MCNAUGHTQN et al.II. EXPERIMENTAL METHODThe experimental method used for this measurementis identical to that used for our recent measurement at788 MeV and is described in detail in our previous paper[8]. Briefly, polarized protons from the LAMPF acceler-ator are used to produce a polarized neutron beam viathe ~H(p, n) reaction from liquid deuterium. The polar-ized neutrons are precessed to L or S spin (parallel orperpendicular to the momentum vector in the horizontalscattering plane) by a dipole magnet and collimated ontoa liquid-hydrogen target. Elastically scattered neutronsand protons are detected by a neutron detector [9] andby the Scylla magnetic spectrometer. The 30' verticalbend in Scylla precessed the L-spin component throughapproximately 90' while leaving the S-spin componentunchanged, thus allowing us to measure both the L andS components (Pl, and Ps) with the Janus carbon po-larimeter [10—12]. If BI, is the L-spin component of theneutron beam then the spin transfer parameter KLs isdefined byI&I,s = Ps/Bl,and similarly for KLL& E~sL and KssThe sign conventions are confusing, so Table I fromour previous paper is included here to define these pa-rameters in terms of Amdt's widely used sAID scatter-ing analysis and phase-shift program [13] and in termsof the comprehensive review paper by Bystricky, Lehar,and Winternitz [14].A. Spin direction(ILLS + ICSL)/(I'LL —I&ss) = tan Ol bTABLE I. Sign convention and notation.This paperAgs~LL~ss~SLAmdtATAPTRTRPTBystricky—&o xo+~oa~o+~oaso—~o~.oThe spin direction of the 788-MeV polarized neutronbeam at LAMPF as measured in our earlier experiment[8] disagreed by 1.5 standard deviations from previousmeasurements [15] and this disagreement was discussedin detail in Sec. II H of Ref. [8]. Following the proceduresof Spinka [15] we determine a neutron-spin precession inthe line-B bending magnets LBBM6 and 7 (see Fig. 1) of0.0307p/P deg, where p is the beam proton momentum inMeV/c and P = v/c is the neutron velocity. The preces-sion in the newly installed permanent magnet BRBMOwas measured and found to be 12.3/P deg.The neutron-spin direction was determined with theneutron polarimeter (QPAN) and the data at 485, 635,and 788 MeV were consistent with these equations withinthe uncertainty of +0.5'. Also, as in the 788-MeV paper[8], we used the relationC.DzTarget. BRBMOVeut, ron beamFIG. 1. Layout of BR neutron-production beam line atLAMPF. The primary proton beam is swept aside by LBBM6and 7. The neutron beam is precessed by the fringes ofLBBM6 and 7 and by BRBMO.to calculate a correction to the spin direction that wouldminimize yz. This agreed both with QPAN and withthe above equations within the statistical uncertainty of+1.2'.In summary the present spin-precession data are con-sistent with our earlier paper [8] but differ by 1.5 stan-dard deviations from the older data [15]. We have as-signed the same 0.7' uncertainty to the spin direction asfor the 788-MeV data.B. BackgroundAs in our previous measurement [8] good np elasticevents were selected by cuts on proton momentum andboth incident neutron and scattered proton time of flight.The final data were obtained without requiring the neu-tron detector in coincidence, but the neutron detectorwas used as a check on the background.The background measured by extrapolating under thepeak of good events was less than 2%. We measuredthe spin transfer for the background in the tails of themomentum spectra to be 0.6 6 0.1 times that for theelastic events so this implies background corrections ofI'% or less.Data acquired with a neutron in coincidence had lessbackground (see Fig. 2 of our previous paper [8])but hadlarger statistical uncertainties. The average ratio of thespin-transfer parameters measured with and without theneutron detector in coincidence was 1,04+0.02, comparedwith a ratio of 1.00 + 0.01 at 788 MeV.The main sources of background are the plastic win-dows of the liquid-hydrogen target. There are three win-dows that are visible to the detectors with a total thick-ness of 0.16 g/cm2 of plastic compared with 2.5 g/cmof liquid hydrogen. Since plastic is approximately halfneutrons and half protons, and since half of the protonsare shadowed within the nucleus, the background frombound protons is 0.04/2. 5 = 1.6%. The spin transfer forquasifree scattering from bound protons is expected tobe similar to free scattering. So we estimate that back-ground corrections are less than 1%. No background cor-rections have been made to the data, but an uncertaintyof 1% has been added quadratically to the overall nor-malization uncertainty (Sec. III) to account for the back-ground.46 np ELASTIC SPIN-TRANSFER MEASUREMENTS AT 485 AND. . . 49TABLE II. Spin-transfer parameters from np elastic scattering at 635 MeV. The overall nor-malization uncertainty is 2%%uo.(deg)178.03176.46174.82170.31168.63166.71159.58157.59155.43148.23146.15143.75137.53134.70131.65126.67123.49120.10115.89112.85109.38105.27102.0198.6194.7191.5688.2084.8381.7178.3474.5571.3468.1165.1862.1959.1555.9453,0450.13(«s)0.851.532.244.194.925.758.859.7210.6613.8214.7415.8018.5719.8321.2123.4724.9226.4828.4329.8531.4833.4334.9936.6338.5240.0741.7343.4144.9946.7048.6450.2951.9853.5155.1056.7158.4460.0061.58Kl.s-0.012+0.0400.038+0.0560.009+0.0460.049+0.0570.117+0.0570.055+0.057-0.034+0.0520.003+0.0470.004+0.047-0.098+0.054-0.091+0.048-0.119+0.044-0,262+0.033-0.239+0.031-0.208+0.031-0.302+0.038-0.321+0.036-0.217+0.034-0.281+0.036-0.278+0.036-0.268+0.029-0.282+0.042-0.315+0.040-0.324+0.038-0.339+0.039-0.231+0.040-0.242+0.035-0.236+0.037-0.217+0.033-0.182+0.031-0.210+0.039-0.134+0.041-0.187+0.051-0.037+0.032-0.068+0.041-0.008+0.0470.021+0.0600.091+0.0680.086+0.093KLL-0.555+0.031-0.494+0.038-0.506+0.031-0.385+0.057-0.295+0.057-0.338+0.057-0.325+0.052-0.300+0.047-0.482+0.047-0.562+0.055-0.545+0.050-0.625+0.046-0.650+0.036-0.642+0.033-0.688+0.033-0.789+0.039-0.704+0.038-0.687+0.036-0.643+0.039-0.631+0.039-0.612+0.032-0.570+0.046-0.559+0.042-0.505+0.040-0.511+0.042-0.392+0.040-0.395+0.037-0.265+0.040-0.240+0.035-0.272+0.032-0.186+0.042-0.134+0.043-0.092+0.054-0.075+0.036-0.143+0.045-0.064+0.052-0.028+0.0680.047+0.075-0.072+0.099Kss-0.042+0.061-0.073+0.077-0.169+0.072-0.519+0.053-0.612+0.054-0.732+0.054-0.586+0.057-0.465+0.052-0.508+0.049-0.190+0.056-0.146+0.052-0.033+0.0460.035+0.0370.113+0.0350.096+0.0350.109+0.0350.107+0.0350.143+0.0330.044+0.0380.059+0.0380.006+0.031-0.065+0.039-0.009+0.036-0.064+0.034-0.037+0.042-0.082+0.039-0.121+0.035-0.090+0.038-0.109+0.036-0.160+0.031-0.042+0.039-0,196+0.041-0.166+0.052-0.136+0.033-0.197+0.066-0.099+0.046-0.134+0.0620.029+0,0570.024+0.075Ksg-0.005+0.047-0.048+0.059-0.085+0.0590.119+0.0550.053+0.0530.075+0.0530.118+0.0560.026+0.0520.057+0.0490.021+0.0560.047+0.0520.092+0.0470.034+0.039-0.008+0.036-0.016+0.036-0.045+0.037-0.096+0.037-0.053+0.034-0.143+0.040-0.041+0.039-0.104+0.032-0.094+0.041-0.027+0.037-0.055+0.0400.096+0.0450.053+0.0410.096+0.0360.100+0.0400.070+0.0350.083+0.0330.043+0.0280.099+0.0440.078+0.0540.156+0.0360.089+0.0430.113+0.049-0.012+0.0570.013+0.061-0.047+0,080TABLE III. Spin-transfer parameters from np elastic scattering at 485 MeV. The overall nor-malization uncertainty is 270.(«g)176.1157.0146.5135.4114.293.174.2~lab(«g)1.710.315.020.130.040.249.7Kgs0.034+0.0460.094+0.030-0.006+0.028-0.184+0.030-0.347+0.039-0.133+0.043-0.038+0.084-0.450+0.029-0.309+0.031-0.449+0.031-0.590+0.032-0.524+0.041-0.345+0.046-0.016+0.091Kss-0.220+0.062-0.659+0.036-0.469+0.040-0.134+0.0320.190+0.040Ksg0.000+0.050-0.014+0.0340.044+0.0390.069+0.033-0.092+0.04150 K. H. MCNAUGHTON et al. 460 ry 1' T ] I T~~T T ~+~ l~ wT 1 1 UQ T~ Q T T T '] T ~T0.2010.0—0.1—0.2 / KLs010.0—0.1—0.2 Ks~ii II,+,; -.iie' .-!jII Q- 31~I-&i—0.3— 0.4BuggAmdt C650—0.3 BuggAmdt C650—0.4.J.. l .l J. J. LJ L 2 ~2 L J.Z J.Z J j ~J 0 LZ 2 l J.. J J20 40 60 80 100 120 140 160 1800, de0 5 I i i I i i & I0 20 40 60 80 100 120 140 160 1800, deFIG. 2. Spin-transfer observables KLS at 635 MeV com-pared with recent phase-shift fits by Amdt and Bugg.FIG. 5. Spin-transfer observables KSL at 635 MeV com-pared with recent phase-shift fits by Amdt and Bugg.I f tiI i I0.1—0.10.1—0.1—0.5 KLLBuggAmdt C650—0.3—0.5I-BuggAmdt C500LAMPF E876Axen Data0 20 40 60 80 100 120 140 160 1800, (de)07 ~~~ ~~ L ~i~1. ~~l i i i l i i.i . i.i . l0 20 40 60 80 100 120 140 160 1800, deFIG. 3. Spin-transfer observables KLL at 635 MeV com-pared with recent phase-shift fits by Amdt and Bugg.FIG. 6. Spin-transfer observables KLS at 485 MeV withAxen's data, compared with recent phase-shift fits by Amdtand Bugg.0. T ~" ' I I " t0.1 0.1—0.1 —0.1—0.5 Kss —0.5 KpL—0.9BuggAmdt C650—0.7—0.9BuggAmdt C5000 20 40 60 80 100 120 140 160 1800, (de )0 20 40l ~~~M~~ ~ l i i i i i i I i i i l60 80 100 120 140 160 1800, (de )FIG. 4. Spin-transfer observables KSS at 635 MeV com-pared with recent phase-shift fits by Amdt and Bugg.FIG. 7. Spin-transfer observables KLL at 485 MeV corn-pared with recent phase-shift fits by Amdt and Bugg.46 np ELASTIC SPIN-TRANSFER MEASUREMENTS AT 485 AND. . . 510.3 0.3 I III I iII I III I0.1—0.1—0.30.1—0.1—0.5—0.7KssBuggAmdt C500 —0.5BuggAmdt C500—0.9—1.10LAMPF E876Axen DataI i s i I r» I » i I i t. i I i i i I » i I20 40 60 80 100 120 140 160 180I9, (de )—0.70 20 40 60 80 100 1208, de140 160 180FIG. 8. Spin-transfer observables KSS at 485 MeV withAxen's data, compared with recent phase-shift fits by Amdtand Bugg.FIG. 9. Spin-transfer observables KSL at 485 MeV com-pared with recent phase-shift fits by Amdt and Bugg.III. NORMALIZATIONAs discussed in detail in Ref. [8] the overall normal-ization is tied to the measurement [16] of KL,L, for thezH(p, n) reaction, which has a 1.8% uncertainty. Whenwe add quadratically the 1% uncertainty in backgroundsubtraction as discusssed in Sec. IIB, the total normal-ization uncertainty is 2%.The remeasurement of the LAMPF neutron-beam po-larization [16] also affects the normalization of much ofthe previous LAMPF spin-dependent data, as discussedin Ref. [16].IV. RESULTS AND PREVIOUS DATAThe measured observables are de6ned in Table I, listedin Tables II and III, and are illustrated in Figs. 2—9 incomparison with recent phase-shift analyses before [13]and after [1] including these data.There are two previous measurements of spin-transferparameters near these energies. Leung [17] measuredEpg and KpL, at 520 and 600 MeV at Berkeley in 1970.The 635-MeV data reported in this paper have ten timesthe number of points and one quarter the uncertainty foreach point, i.e. , more than one hundred times the statis-tical weight as Leung's data. Axen [18] measured Kssand Er,s at 495 MeV at TRIUMF in 1980. Axen's dataare generally in agreement with our 485-MeV data.ACKNOWLEDGMENTSThis work was supported in part by the U.S. De-partment of Energy Contracts No. W-7405-ENG-36and No. W-31-109-ENG-38, by Grants No. DE-FG05-88ER40446 and No. DE-FG05-88ER40399, and by theNational Science Foundation. One of the authors(R.H.J.) was suported by Argonne National Laboratoryas a faculty research participant under a program admin-istered by the Argonne Division of Educational Programswith funding provided by the U.S. Department of Energy.[1] D.V. Bugg and R.A. Bryan, Nucl. Phys. A (to be pub-lished).[2] C.R. Newsom et a!., Phys. Rev. C 39, 965 (1989).[3] J. Ball et al. , Z. Phys. C 40, 193 (1988).[4] R. Garnett et al. , Phys. Rev. D 40, 1708 (1989).[5] M.W. Rawool, thesis, Los Alamos Report LA-11491-T(1989); submitted to Phys. Rev. D.[6] T. Shima et al , submitted to. Phys. Rev. D.[7] H. Spinka, Phys. Rev. D 30, 1461 (1984).[8] M.W. McNaughton et al. , Phys. Rev. C 44, 2267 (1991).[9] R. Garnett et al. , Nucl. Instrum. Methods 309, 508(1991).[10] R.D. Ransome, S.J. Greene, C.L. Hollas, B.E. Bonner,M.W. McNaughton, C.L. Morris, and H.A. Thiessen,Nucl. Instrum. Methods 201, 309 (1982).[11] R.D. Ransome et al. , Nucl. Instrum. Methods 201, 315(1982).[12] M.W. McNaughton et al. , Nucl. Instrum. MethodsA241, 435 (1985).[13] R.A. Amdt, Phys. Rev. D 35, 128 (1987).[14] J. Bystricky, F. Lehar, and P. Winternitz, J. Phys.(Paris) 39, 1 (1978).[15] H. Spinka, Argonne National Lab Report ANL-HEP-TR-85-35 (1985).[16] M.W. McNaughton et al. , Phys. Rev. C 45, 2564 (1992).[17) K.C. Leung, UC Berkeley Ph. D. thesis [Report UCRL19705 (1970)].[18] D. Axen et a/. , Phys. Rev. C 21, 998 (1980).[19) J. Bystricky, C. Lechanoine-Leluc, and F. Lehar, J. Phys.(Paris) 48, 199 (1987); 51, 2747 (1990).

np elastic spin-transfer measurements at 485 and 635 MeV

Texas A&M University

PHYSICAL REVIEW C VOLUME 46, NUMBER 1 JULY 1992
ARTICLES
np elastic spin-transfer measurements at 485 and 635 MeV
K. H. McNaughton, D. A. Ambrose, P. Coffey, K. 3ohnston, ' and P. J. Riley
University of Texas, Austin, Texas 78719
M. W. McNaughton, K. Koch, t I. Supek, and N. Tanaka~
Los Alamos National Laboratory, Los Alamos, Nenes Mexico 87$$$
G. Glass, J. C. Hiebert, L. C. Northcliffe, and A. J. Simon
Texas ASM Universa ty, C'ollege Station, Texas 778/8
D. J. Mercer
University of Colorado, Boulder, Colorado 80808
D. L. Adams
Rice University, Houston, Texas 77251
H. Spinka
Argonne National Laboratory, Argonne, Illinois 80/89
R. H. Jeppesen
University of Montana, Missoula, Montana $9818
G. E. Tripard
Washington State University, Pullman, Washington 99I8$
H. Woolverton
University of Central Arkansas, Con+ay, Arkansas 780M
(Received 27 March 1992)
We have measured the spin-transfer parameters E~I., E~l. , Al. p, and Egg at 635 MeV from 50'
to 178' c.m. and at 485 MeV from 74' to 176' c.m. These new data have a significant impact on the
phase-shift analyses. There are now sufticient data near these energies to overdetermine the elastic
nucleon-nucleon amplitudes.
PACS number(s): 21.30.+y, 13.75.Cs, 24.70.+s
I. INTRODUCTION
The 1991 status of the np elastic phase-shift analy-
sis near 650 MeV was summarized by Bugg and Bryan
[1] as follows. "There are not enough accurate spin-
dependent data to give a secure solution and most of
the phase shifts are strongly correlated, with correlation
'Current Address: Los Alamos National Laboratory, Los
Alamos, NM 87545.
t Current Address: PSI, LG I25, CH 5232 Villigen PSI,
Switzerland.
~ Deceased.
coefficients as high as 76%." "To stabilize the solution,
Wolfenstein (spin-transfer) parameter data are required
of similar quality to those at 800 MeV. " We present these
new data here. With the inclusion of these data, Bugg
reports stable solutions with small correlations at 650
MeV.
Previous spin-dependent data near 650 MeV include
the analyzing power [2], the four spin-correlation parame-
ters [3—6], and the four spin-transfer parameters reported
here. These data are sufhcient to over determine the elas-
tic nucleon-nucleon amplitudes [7].
Previous measurements of the spin-transfer param-
eters are discussed in Sec. IV. The normalization of
both present and previous LAMPF data is discussed in
Sec. III.
46 47 1992 The American Physical Society
48 K. H. MCNAUGHTQN et al.
II. EXPERIMENTAL METHOD
The experimental method used for this measurement
is identical to that used for our recent measurement at
788 MeV and is described in detail in our previous paper
[8]. Briefly, polarized protons from the LAMPF acceler-
ator are used to produce a polarized neutron beam via
the ~H(p, n) reaction from liquid deuterium. The polar-
ized neutrons are precessed to L or S spin (parallel or
perpendicular to the momentum vector in the horizontal
scattering plane) by a dipole magnet and collimated onto
a liquid-hydrogen target. Elastically scattered neutrons
and protons are detected by a neutron detector [9] and
by the Scylla magnetic spectrometer. The 30' vertical
bend in Scylla precessed the L-spin component through
approximately 90' while leaving the S-spin component
unchanged, thus allowing us to measure both the L and
S components (Pl, and Ps) with the Janus carbon po-
larimeter [10—12]. If BI, is the L-spin component of the
neutron beam then the spin transfer parameter KLs is
defined by
I&I,s = Ps/Bl,
and similarly for KLL& E~sL and Kss
The sign conventions are confusing, so Table I from
our previous paper is included here to define these pa-
rameters in terms of Amdt's widely used sAID scatter-
ing analysis and phase-shift program [13] and in terms
of the comprehensive review paper by Bystricky, Lehar,
and Winternitz [14].
A. Spin direction
(ILLS + ICSL)/(I'LL —I&ss) = tan Ol b
TABLE I. Sign convention and notation.
This paper
Ags
~LL
~ss
~SL
Amdt
AT
APT
RT
RPT
Bystricky
—&o xo
+~oa~o
+~oaso
—
~o~.o
The spin direction of the 788-MeV polarized neutron
beam at LAMPF as measured in our earlier experiment
[8] disagreed by 1.5 standard deviations from previous
measurements [15] and this disagreement was discussed
in detail in Sec. II H of Ref. [8]. Following the procedures
of Spinka [15] we determine a neutron-spin precession in
the line-B bending magnets LBBM6 and 7 (see Fig. 1) of
0.0307p/P deg, where p is the beam proton momentum in
MeV/c and P = v/c is the neutron velocity. The preces-
sion in the newly installed permanent magnet BRBMO
was measured and found to be 12.3/P deg.
The neutron-spin direction was determined with the
neutron polarimeter (QPAN) and the data at 485, 635,
and 788 MeV were consistent with these equations within
the uncertainty of +0.5'. Also, as in the 788-MeV paper
[8], we used the relation
C.Dz
Target. BRBMO
Veut, ron beam
FIG. 1. Layout of BR neutron-production beam line at
LAMPF. The primary proton beam is swept aside by LBBM6
and 7. The neutron beam is precessed by the fringes of
LBBM6 and 7 and by BRBMO.
to calculate a correction to the spin direction that would
minimize yz. This agreed both with QPAN and with
the above equations within the statistical uncertainty of
+1.2'.
In summary the present spin-precession data are con-
sistent with our earlier paper [8] but differ by 1.5 stan-
dard deviations from the older data [15]. We have as-
signed the same 0.7' uncertainty to the spin direction as
for the 788-MeV data.
B. Background
As in our previous measurement [8] good np elastic
events were selected by cuts on proton momentum and
both incident neutron and scattered proton time of flight.
The final data were obtained without requiring the neu-
tron detector in coincidence, but the neutron detector
was used as a check on the background.
The background measured by extrapolating under the
peak of good events was less than 2%. We measured
the spin transfer for the background in the tails of the
momentum spectra to be 0.6 6 0.1 times that for the
elastic events so this implies background corrections of
I'% or less.
Data acquired with a neutron in coincidence had less
background (see Fig. 2 of our previous paper [8])but had
larger statistical uncertainties. The average ratio of the
spin-transfer parameters measured with and without the
neutron detector in coincidence was 1,04+0.02, compared
with a ratio of 1.00 + 0.01 at 788 MeV.
The main sources of background are the plastic win-
dows of the liquid-hydrogen target. There are three win-
dows that are visible to the detectors with a total thick-
ness of 0.16 g/cm2 of plastic compared with 2.5 g/cm
of liquid hydrogen. Since plastic is approximately half
neutrons and half protons, and since half of the protons
are shadowed within the nucleus, the background from
bound protons is 0.04/2. 5 = 1.6%. The spin transfer for
quasifree scattering from bound protons is expected to
be similar to free scattering. So we estimate that back-
ground corrections are less than 1%. No background cor-
rections have been made to the data, but an uncertainty
of 1% has been added quadratically to the overall nor-
malization uncertainty (Sec. III) to account for the back-
ground.
46 np ELASTIC SPIN-TRANSFER MEASUREMENTS AT 485 AND. . . 49
TABLE II. Spin-transfer parameters from np elastic scattering at 635 MeV. The overall nor-
malization uncertainty is 2%%uo.
(deg)
178.03
176.46
174.82
170.31
168.63
166.71
159.58
157.59
155.43
148.23
146.15
143.75
137.53
134.70
131.65
126.67
123.49
120.10
115.89
112.85
109.38
105.27
102.01
98.61
94.71
91.56
88.20
84.83
81.71
78.34
74.55
71.34
68.11
65.18
62.19
59.15
55.94
53,04
50.13
(«s)
0.85
1.53
2.24
4.19
4.92
5.75
8.85
9.72
10.66
13.82
14.74
15.80
18.57
19.83
21.21
23.47
24.92
26.48
28.43
29.85
31.48
33.43
34.99
36.63
38.52
40.07
41.73
43.41
44.99
46.70
48.64
50.29
51.98
53.51
55.10
56.71
58.44
60.00
61.58
Kl.s
-0.012+0.040
0.038+0.056
0.009+0.046
0.049+0.057
0.117+0.057
0.055+0.057
-0.034+0.052
0.003+0.047
0.004+0.047
-0.098+0.054
-0.091+0.048
-0.119+0.044
-0,262+0.033
-0.239+0.031
-0.208+0.031
-0.302+0.038
-0.321+0.036
-0.217+0.034
-0.281+0.036
-0.278+0.036
-0.268+0.029
-0.282+0.042
-0.315+0.040
-0.324+0.038
-0.339+0.039
-0.231+0.040
-0.242+0.035
-0.236+0.037
-0.217+0.033
-0.182+0.031
-0.210+0.039
-0.134+0.041
-0.187+0.051
-0.037+0.032
-0.068+0.041
-0.008+0.047
0.021+0.060
0.091+0.068
0.086+0.093
KLL
-0.555+0.031
-0.494+0.038
-0.506+0.031
-0.385+0.057
-0.295+0.057
-0.338+0.057
-0.325+0.052
-0.300+0.047
-0.482+0.047
-0.562+0.055
-0.545+0.050
-0.625+0.046
-0.650+0.036
-0.642+0.033
-0.688+0.033
-0.789+0.039
-0.704+0.038
-0.687+0.036
-0.643+0.039
-0.631+0.039
-0.612+0.032
-0.570+0.046
-0.559+0.042
-0.505+0.040
-0.511+0.042
-0.392+0.040
-0.395+0.037
-0.265+0.040
-0.240+0.035
-0.272+0.032
-0.186+0.042
-0.134+0.043
-0.092+0.054
-0.075+0.036
-0.143+0.045
-0.064+0.052
-0.028+0.068
0.047+0.075
-0.072+0.099
Kss
-0.042+0.061
-0.073+0.077
-0.169+0.072
-0.519+0.053
-0.612+0.054
-0.732+0.054
-0.586+0.057
-0.465+0.052
-0.508+0.049
-0.190+0.056
-0.146+0.052
-0.033+0.046
0.035+0.037
0.113+0.035
0.096+0.035
0.109+0.035
0.107+0.035
0.143+0.033
0.044+0.038
0.059+0.038
0.006+0.031
-0.065+0.039
-0.009+0.036
-0.064+0.034
-0.037+0.042
-0.082+0.039
-0.121+0.035
-0.090+0.038
-0.109+0.036
-0.160+0.031
-0.042+0.039
-0,196+0.041
-0.166+0.052
-0.136+0.033
-0.197+0.066
-0.099+0.046
-0.134+0.062
0.029+0,057
0.024+0.075
Ksg
-0.005+0.047
-0.048+0.059
-0.085+0.059
0.119+0.055
0.053+0.053
0.075+0.053
0.118+0.056
0.026+0.052
0.057+0.049
0.021+0.056
0.047+0.052
0.092+0.047
0.034+0.039
-0.008+0.036
-0.016+0.036
-0.045+0.037
-0.096+0.037
-0.053+0.034
-0.143+0.040
-0.041+0.039
-0.104+0.032
-0.094+0.041
-0.027+0.037
-0.055+0.040
0.096+0.045
0.053+0.041
0.096+0.036
0.100+0.040
0.070+0.035
0.083+0.033
0.043+0.028
0.099+0.044
0.078+0.054
0.156+0.036
0.089+0.043
0.113+0.049
-0.012+0.057
0.013+0.061
-0.047+0,080
TABLE III. Spin-transfer parameters from np elastic scattering at 485 MeV. The overall nor-
malization uncertainty is 270.
(«g)
176.1
157.0
146.5
135.4
114.2
93.1
74.2
~lab
(«g)
1.7
10.3
15.0
20.1
30.0
40.2
49.7
Kgs
0.034+0.046
0.094+0.030
-0.006+0.028
-0.184+0.030
-0.347+0.039
-0.133+0.043
-0.038+0.084
-0.450+0.029
-0.309+0.031
-0.449+0.031
-0.590+0.032
-0.524+0.041
-0.345+0.046
-0.016+0.091
Kss
-0.220+0.062
-0.659+0.036
-0.469+0.040
-0.134+0.032
0.190+0.040
Ksg
0.000+0.050
-0.014+0.034
0.044+0.039
0.069+0.033
-0.092+0.041
50 K. H. MCNAUGHTON et al. 46
0 ry 1' T ] I T~~T T ~+~ l~ wT 1 1 UQ T~ Q T T T '] T ~T
0.2
01
0.0
—0.1
—0.2 / KLs
01
0.0
—0.1
—0.2 Ks~
ii II
,+,; -.iie' .-!j
II Q- 31~I
-&i
—0.3
— 0.4
Bugg
Amdt C650
—0.3 Bugg
Amdt C650
—0.4
.J.. l .l J. J. LJ L 2 ~2 L J.Z J.Z J j ~J 0 LZ 2 l J.. J J
20 40 60 80 100 120 140 160 180
0, de
0 5 I i i I i i & I
0 20 40 60 80 100 120 140 160 180
0, de
FIG. 2. Spin-transfer observables KLS at 635 MeV com-
pared with recent phase-shift fits by Amdt and Bugg.
FIG. 5. Spin-transfer observables KSL at 635 MeV com-
pared with recent phase-shift fits by Amdt and Bugg.
I f t
i
I i I
0.1
—0.1
0.1
—0.1
—0.5 KLL
Bugg
Amdt C650
—0.3
—0.5
I-
Bugg
Amdt C500
LAMPF E876
Axen Data
0 20 40 60 80 100 120 140 160 180
0, (de)
07 ~~~ ~~ L ~i~1. ~~l i i i l i i.i . i.i . l
0 20 40 60 80 100 120 140 160 180
0, de
FIG. 3. Spin-transfer observables KLL at 635 MeV com-
pared with recent phase-shift fits by Amdt and Bugg.
FIG. 6. Spin-transfer observables KLS at 485 MeV with
Axen's data, compared with recent phase-shift fits by Amdt
and Bugg.
0. T ~" ' I I " t
0.1 0.1
—0.1 —0.1
—0.5 Kss —0.5 KpL
—0.9
Bugg
Amdt C650
—0.7
—0.9
Bugg
Amdt C500
0 20 40 60 80 100 120 140 160 180
0, (de )
0 20 40
l ~~~M~~ ~ l i i i i i i I i i i l
60 80 100 120 140 160 180
0, (de )
FIG. 4. Spin-transfer observables KSS at 635 MeV com-
pared with recent phase-shift fits by Amdt and Bugg.
FIG. 7. Spin-transfer observables KLL at 485 MeV corn-
pared with recent phase-shift fits by Amdt and Bugg.
46 np ELASTIC SPIN-TRANSFER MEASUREMENTS AT 485 AND. . . 51
0.3 0.3 I I
I
I I i
I
I I I
I
I I
0.1
—0.1
—0.3
0.1
—0.1
—0.5
—0.7
Kss
Bugg
Amdt C500 —0.5
Bugg
Amdt C500
—0.9
—1.1
0
LAMPF E876
Axen Data
I i s i I r» I » i I i t. i I i i i I » i I
20 40 60 80 100 120 140 160 180
I9, (de )
—0.7
0 20 40 60 80 100 120
8, de
140 160 180
FIG. 8. Spin-transfer observables KSS at 485 MeV with
Axen's data, compared with recent phase-shift fits by Amdt
and Bugg.
FIG. 9. Spin-transfer observables KSL at 485 MeV com-
pared with recent phase-shift fits by Amdt and Bugg.
III. NORMALIZATION
As discussed in detail in Ref. [8] the overall normal-
ization is tied to the measurement [16] of KL,L, for the
zH(p, n) reaction, which has a 1.8% uncertainty. When
we add quadratically the 1% uncertainty in background
subtraction as discusssed in Sec. IIB, the total normal-
ization uncertainty is 2%.
The remeasurement of the LAMPF neutron-beam po-
larization [16] also affects the normalization of much of
the previous LAMPF spin-dependent data, as discussed
in Ref. [16].
IV. RESULTS AND PREVIOUS DATA
The measured observables are de6ned in Table I, listed
in Tables II and III, and are illustrated in Figs. 2—9 in
comparison with recent phase-shift analyses before [13]
and after [1] including these data.
There are two previous measurements of spin-transfer
parameters near these energies. Leung [17] measured
Epg and KpL, at 520 and 600 MeV at Berkeley in 1970.
The 635-MeV data reported in this paper have ten times
the number of points and one quarter the uncertainty for
each point, i.e. , more than one hundred times the statis-
tical weight as Leung's data. Axen [18] measured Kss
and Er,s at 495 MeV at TRIUMF in 1980. Axen's data
are generally in agreement with our 485-MeV data.
ACKNOWLEDGMENTS
This work was supported in part by the U.S. De-
partment of Energy Contracts No. W-7405-ENG-36
and No. W-31-109-ENG-38, by Grants No. DE-FG05-
88ER40446 and No. DE-FG05-88ER40399, and by the
National Science Foundation. One of the authors
(R.H.J.) was suported by Argonne National Laboratory
as a faculty research participant under a program admin-
istered by the Argonne Division of Educational Programs
with funding provided by the U.S. Department of Energy.
[1] D.V. Bugg and R.A. Bryan, Nucl. Phys. A (to be pub-
lished).
[2] C.R. Newsom et a!., Phys. Rev. C 39, 965 (1989).
[3] J. Ball et al. , Z. Phys. C 40, 193 (1988).
[4] R. Garnett et al. , Phys. Rev. D 40, 1708 (1989).
[5] M.W. Rawool, thesis, Los Alamos Report LA-11491-T
(1989); submitted to Phys. Rev. D.
[6] T. Shima et al , submitted to. Phys. Rev. D.
[7] H. Spinka, Phys. Rev. D 30, 1461 (1984).
[8] M.W. McNaughton et al. , Phys. Rev. C 44, 2267 (1991).
[9] R. Garnett et al. , Nucl. Instrum. Methods 309, 508
(1991).
[10] R.D. Ransome, S.J. Greene, C.L. Hollas, B.E. Bonner,
M.W. McNaughton, C.L. Morris, and H.A. Thiessen,
Nucl. Instrum. Methods 201, 309 (1982).
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(1982).
[12] M.W. McNaughton et al. , Nucl. Instrum. Methods
A241, 435 (1985).
[13] R.A. Amdt, Phys. Rev. D 35, 128 (1987).
[14] J. Bystricky, F. Lehar, and P. Winternitz, J. Phys.
(Paris) 39, 1 (1978).
[15] H. Spinka, Argonne National Lab Report ANL-HEP-TR-
85-35 (1985).
[16] M.W. McNaughton et al. , Phys. Rev. C 45, 2564 (1992).
[17) K.C. Leung, UC Berkeley Ph. D. thesis [Report UCRL
19705 (1970)].
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np elastic spin-transfer measurements at 485 and 635 MeV

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np elastic spin-transfer measurements at 485 and 635 MeV

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