Multiplicity and angular distributions of charged particles in interactions of Fe in emulsion at 2.5A GeV/c

Data are presented on multiplicity and angular distributions of charged secondary particles from inelastic interactions of ⁵⁶Fe in emulsion at 2.5A GeV/c. Comparisons with data, at nearby the same incident momentum per nucleon from p-A, ¹⁴N-A, ¹⁶O-A and ⁴⁰Ar-A collisions are performed in order to trace the dependence on projectile and target mass. Furthermore, the ⁵⁶Fe data are compared with the results from a cascade-evaporation model. This comparison shows some significant deviations between the model and the data which are not observed for light ion induced collisions.     

Reaction filters. Charged-particle multiplicity and linear momentum transfer

The relation between charged-particle multiplicity and linear momentum transfer to heavy reaction residues has been investigated with a 4π charged-particle detector for the reactions ³⁶Ar+²³⁸U at E/A=35 MeV and ¹⁴N+²³⁸U at E/A=50 MeV. The multiplicity of charged particles at backward angles (θ > 35°) incrreases linear momentum transfer while the multiplicity of charged particles in the forward direction is almost independent of the linear momentum transfer.     

Investigation of the HFS in the 4d 5p zP3,4 states of Mo and Mo by levelcrossing spectroscopy

The hyperfine structures of the z⁷P₃ and z⁷P₄ states of ⁹⁵Mo and ⁹⁷Mo have been investigated by levelcrossing spectroscopy. A fit of the experimental signal curves yields the magnetic and electric hfs coupling constants: ⁹⁵Mo z⁷P₃ |A| = 86.19(10) MHz, |B|=5.2(30) MHz, A/B0⁹⁵Mo z⁷P₄ |A|=64.05(30) MHz, |B|=4.3(30) MHz, A/B<0; ⁹⁷Mo z⁷P₃|A|= 88.0(1) MHz, |B|=60.0(20) MHz, A/B<0; ⁹⁷Mo z⁷P₄ |A|=65.4(3) MHz, |B|=50.0(50) MHz, A/B0. For the ratio of the electric quadrupole moments we fine ⁹⁷Q/⁹⁵ Q= -11.5(70).     

Hyperon-Nucleon bound states and electroproduction of strangeness on He

The A(e, e′K⁺)YX reaction has been investigated in Hall C at Jefferson Lab. Data were taken for Q² ≈ 0.35 and 0.5 GeV² at a beam energy of 3.245 GeV for ³He, ⁴He. The missing mass spectra are fitted with Monte Carlo simulations including Λ, Σ⁰, Σ⁻ hyperon production. Models for quasifree production are compared to the data, excess yields close to threshold are attributed to FSI. Evidence for Λ-hypernuclear bound states is seen for ^3,4He targets.     

Towards a better understanding of O nuclear structure: Muon capture and radiative pion capture reactions

Muon capture and radiative pion capture reactions on ¹⁶O have been analysed with the aim to extract more information on the importance of higher components of the A = 16 nuclear ground and excited states. Good agreement with the experimental data for both reactions may be achieved if at least 2p2h components of the nuclear wave functions are taken into account. The positive parity excited states in ¹⁶N are shown to contribute 43 % to the radiative π⁻ capture but only ≈ 10 % to the muon capture rate.     

Multiplicity and average PT of central nucleus-nucleus collisions

We evaluated the multiplicity and average P_T of central nucleus-nucleus collisions using an extension of the Glauber model and theoretical ideas coming from particle-nucleus interactions. The multiplicity rises with the number of nucleons of the projectile A as c₁A+c₂A^1/3. The average P_T decreases with the number of nucleons B of the target. We discuss our results in connection with the possible phase transition between hadron matter and quark-gluon matter.     

1-forms over the moduli space of irreducible connections defined by the spectrum of Dirac operators

Let (P) be the moduli space of irreducible connections of a G-principal bundle P over a closed Riemannian spin manifold M. Let D_A be the Dirac operator of M coupled to a connection A of P and f a smooth function on M. We consider a smooth variation A(u) of A with tangent vector ω and denote T_ω:= (D_A(u)−f) (u=0. The coefficients of the asymptotic expansion of trace (T_ω · e^-t(D_A−f)2) near t=0 define 1-forms a^(k)_f, K=0, 1, 2, … on (P). In this paper we calculate aa⁽⁰⁾_f, a⁽¹⁾_f, a⁽²⁾_f and study some of their properties. For instance using the 1-form a⁽²⁾_f for suitable functions f we obtain a foliation of codimension 5 of the space of G-instantons of S⁴.     

Cranked Skyrme–Hartree–Fock calculation for superdeformed and hyperdeformed rotational bands in N=Z nuclei from S to Cr

With the use of the symmetry-unrestricted cranked Skyrme–Hartree–Fock method in the three-dimensional coordinate-mesh representation, we have carried out a systematic theoretical search for the superdeformed and hyperdeformed rotational bands in the mass A=30–50 region. Along the N=Z line, we have found superdeformed solutions in ³²S, ³⁶Ar, ⁴⁰Ca, ⁴⁴Ti, and hyperdeformed solutions in ³⁶Ar, ⁴⁰Ca, ⁴⁴Ti, ⁴⁸Cr. The superdeformed band in ⁴⁰Ca is found to be extremely soft against both the axially symmetric (Y₃₀) and asymmetric (Y₃₁) octupole deformations. An interesting role of symmetry breaking in the mean field is pointed out.     

Minimal renormalization without ε-expansion: Three-loop amplitude functions of the 0(n) symmetric Φ theory in three dimensions below Tc

We present an analytic three-loop calculation for thermodynamic quantities of the O(n) symmetric Φ⁴ theory below T_c within the minimal subtraction scheme at fixed dimension d = 3. Goldstone singularities arising at an intermediate stage in the calculation of O(n) symmetric quantities cancel among themselves leaving a finite result in the limit of zero external field. From the free energy we calculate the three-loop terms of the amplitude functions ƒ_Φ, F₊ and F₋ of the order parameter and the specific heat above and below Tc, respectively, without using the e = 4-d expansion. A Borel resummation for the case n = 2 yields resummed amplitude functions f_Φ and F₋ that are slightly larger than the one-loop results. Accurate knowledge of these functions is needed for testing the renormalization-group prediction of critical-point universality along the λ₋line of superfluid ⁴He. Combining the three-loop result for F₋ with a recent five-loop calculation of the additive renormalization constant of the specific heat yields excellent agreement between the calculated and measured universal amplitude ratio A⁺/A^- of the specific heat of ⁴He. In addition we use our result for f_Φ to calculate the universal combination Rc of the amplitudes of the order parameter, the susceptibility and the specific heat for n = 2 and n = 3. Our Borel-resummed three-loop result for R_c is significantly more accurate than the previous result obtained from the ε-expansion up to O(ε².     

Do we really understand nuclear reactions within thick targets using GeV-hadrons?

Three experimental evidences are presented to show that, using classical concepts of physics, we are unable to understand the interaction of 72 GeV ⁴⁰Ar (and 44 GeV ¹²C) and their relativistic secondary fragments in thick Cu-targets. The first observation is connected with fragmentation products of mass A in the range of 10A40, in particular to the production of more-than-calculated yields of ²⁴Na. The reason for this unexpected behavior is due to some enhanced interaction properties for relativistic secondary fragments. Moreover, due to the observation of constant classical total interaction cross sections for primary and secondary hadrons, this enforces a reduced production of spallation products being close to the target, as is in fact experimentally observed (the second evidence). The third experimental observation is a more-than-linear increase in the production of secondary neutrons for reactions induced by 44 GeV ¹²C in thick Pb- and Cu-targets as compared to 12 GeV ¹²C. This can be understood within the context of the first two experimental evidences. These effects are experimentally confirmed above about 40 GeV for hadronic primaries, however, they may even extend down to 1 GeV primary hadron energy.

Results are discussed within the context of a new theoretical approach.     

水溶液中稀土离子与甘氨酸、丝氨酸、天冬氨酸作用的13C NMR研究

测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的¹³C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm~0.25nm,天冬氨酸的γ-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的¹³C诱导位移的系统分析表明,配体¹³C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C₀)│<│A(C_α)│;A(C₀)为正,A(C_α)为负;(2)│G(C₀)│>│G(C_α)│;配体碳核的G均为负值。     

Analyzing power in the reaction pp→dπ for beam momenta from 1.17 to 1.96 GeV/c

The analyzing power A_y0 in the reaction p↑p→dπ⁺ has been measured using the polarized proton beam at Argonne National Laboratory's zero gradient synchrotron. Data were taken at beam momenta of 1.17, 1.47, 1.70, and 1.96 GeV/c and for pion center of mass angles from 8° to 163°.     

The (He, t) reaction at intermediate energies : Spin-isospin multipole transitions

Data for the (³He, t) reaction at 900 MeV and 2 GeV on the targets ²⁶Mg, ⁴⁰Ca, ⁴⁸Ca, ⁵⁴Fe, ⁹⁰Zr and ²⁰⁸Pb are presented. A multipole decomposition for the data at 900 MeV has been made and the different distributions have been analysed. From the L = 0 cross section the Gamow-Teller strength distributions are extracted and compared with (p, n) data. The L = 1 and 2 distributions are analysed in a schematic model which describes the general systematics fairly well. The spectra at 2 GeV and Θ = 4° show for all targets a well-developed quasi-elastic peak. The A-dependence of the cross section is analysed in a simple model.     

He particle emission in fast neutron induced reactions

Cross sections for some (n, ³He + dp + n2p) and (n, + 2n2p + n³He + pt + dd + dnp) reactions induced by fast neutrons produced via breakup of 53 MeV deuterons on a Be target (E_n = 4–50 MeV; I_max at 22.5 MeV; FWHM = 15.8 MeV) were measured for isotopes of the elements I, La, Nd, Tb, Ho, Yb, W and Au by the activation technique using high-resolution γ-ray spectroscopy, wherever necessary chemical separation, and in several cases enriched isotopes as targets. Furthermore, ³He/ emission cross-section ratios were measured for Co, Ag, In, Cs, La, Ta, Au and Bi using a quadrupole mass spectrometer. The cross sections decrease as a function of increasing (N−Z)/A of the target nucleus. For target elements with Z 44, the ³He/ emission cross-section ratio increases with increasing Z; for elements with Z > 44, however, the trend is reversed. Hauser-Feshbach calculations suggest that the ³He/ emission cross-section ratios are not explainable by the statistical model.     

Pion and proton production in forward and backward hemisphere in C-emulsion interaction at 4.5 GeV/c per nucleon

The paper presents an in-depth study on the forward and backward multiplicity correlations in case of pions and protons (from the target) based on the experimental data on ¹²C-emulsion interaction at 4.5 GeV/c per nucleon. The cumulative distribution of their emission angles in the backward hemisphere is presented. The asymmetry parameter (A) and the forward-backward ratio (F/B) as a function of the number of heavy particles (n_h) is also shown. The results reveal many interesting characteristics regarding the backward particle production.     

The Fermi matrix elements inferred from β-γ(CP) correlation measurements in Fe decay

Measurements have been made of the β-γ circular-polarization correlation paramter A for the 273 keV β-branch in the decay of ⁵⁹Fe. It has recently been established that each of the principal β-branches of ⁵⁹Fe involves ΔJ=0 and thus has a possible non-zero Fermi matrix element M_F which can be determined from the ƒt value and A. Previous β-γ (_CP) measurements on this nucleide have all employed the usual γ-ray scattering technique. This method is suitable for the 475 keV β-branch but does not produce an accurate measurement of the lower energy branch because of energy discrimination difficulties. A transmission polarimeter with γ-discrimination has been used in the present work to obtain clean data on the 273 keV β-1.29 MeV γ-cascade. Calibration with ⁶⁰Co (1.33 MeV) and ²⁸Al (1.79 MeV) yielded A = −0.154±0.023. This gives for the isospin impurity coefficient and the effective Coulomb matrix element of the 1.29 MeV state (1.1±1.4) × 10⁻³ and 9±11 keV, respectively.     

N=2 6-dimensional supersymmetric E6 breaking

We study the N=2 supersymmetric E₆ models on the 6-dimensional space–time where the supersymmetry and gauge symmetry can be broken by the discrete symmetry. On the space–time M⁴×S¹/(Z₂×Z₂′)×S¹/(Z₂×Z₂′), for the zero modes, we obtain the 4-dimensional N=1 supersymmetric models with gauge groups SU(3)×SU(2)×SU(2)×U(1)², SU(4)×SU(2)×SU(2)×U(1), and SU(3)×SU(2)×U(1)³ with one extra pair of Higgs doublets from the vector multiplet. In addition, considering that the extra space manifold is the annulus A² and disc D², we list all the constraints on constructing the 4-dimensional N=1 supersymmetric SU(3)×SU(2)×U(1)³ models for the zero modes, and give the simplest model with Z₉ symmetry. We also comment on the extra gauge symmetry breaking and its generalization.     

Hydrogen depth profile measurement in a-Si1-xCx:H films by elastic recoil detection

The hydrogen content and depth profile in a-Si_1-xC_x:H films were measured by the elastic recoil detection (ERD) technique. It is shown that the hydrogen content changes from 15 to 50 at% with increasing carbon content x. For x<0.4 the hydrogen content increases mainly due to the increase of the Si-CH₃ contribution and for x > 0.4 due to C-H bonds. By combining the ERD and IR results, the proportionality between the number of Si-CH₃ bonds and the intensity of IR absorption due to the Si-CH₃ rocking mode vibration is ascertained. The proportionality constant is found to be A^roc_Si-CH3 = 5 × 10¹⁹ cm^-2.     

Pionic excitation of giant resonances in Y

Inelastic scattering of π⁺ and π⁻ exhibits strongly excited giant resonance structures. Besides the giant quadrupole resonance centered around 14 MeV, structures are observed at 16.8 MeV which can be fitted with a mixing of L=0 and L=1, and around 25 MeV (E_x = 110A^−1/3).     

Trying to catch the elusive A and more. Reactions initiated by b-quarks and the Higgs sector of the MSSM

We study the cross sections for the production of neneural, intermediate mass Higgs boson in the process pp→ tq′φ, pp→tW⁻φ and pp→bZ⁰φ in the Minimal Supersymmetric Standard Model (φ = H⁰, h⁰ and A⁰) at Supercollider energies. The additional heavy particles (t, W, Z) in the final state can be used for tagging purposes, increasing the signal to background ratio. These reactions are dominated by bg and bg fusion. Their relevance for Higgs particle searches is discussed taking into account the expected efficiencies and purities for b-tagging. We find that, for tan β = 30, the cross sections for pp → bZ⁰φ are larger than 14 pb, over the whole intemediate range of M_A⁰, for A⁰ and at least one of the other two Higgses. Therefore this reaction is an excellent candidate for the discovery of one or more MSSM Higgs particles.