Biomedical subjects

H Noumi

Publications and source records attributed to H Noumi.

At least 19 recordsLinked to original sources

PubMed2006

Exclusive measurement of the nonmesonic weak decay of the lambda(5)He hypernucleus.

We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay of lambda(5)He formed via the 6Li(pi+, K+) reaction. The energies of the two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body weak reactions of lambda p --> np and lambda n --> nn, respectively. The ratio of the nucleon pair numbers was N(nn)/N(np) = 0.45 +/- 0.11(stat) +/- 0.03(syst) in the kinematic region of cos theta(NN) < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of gamma(lambda p --> np)/gamma(lambda n --> nn). The ratio is consistent with recent theoretical calculations based on the heavy meson and/or direct-quark exchange picture.

Journal Article↗

PubMed2005

Production of the neutron-rich hypernucleus 10LambdaLi in the (pi-,K+) double charge-exchange reaction.

In order to produce a neutron-rich Lambda hypernucleus for the first time, we carried out an experiment by utilizing the (pi-,K+) double charge-exchange reaction on a 10B target. We observed the production of a 10LambdaLi hypernucleus. The cross section for the Lambda bound region was found to be 11.3+/-1.9 nb/sr with the 1.2 GeV/c incident momentum, which is compared with the 10LambdaB hypernucleus production cross section, 7.8+/-0.3 microb/sr, in the (pi+,K+) reaction with a 1.05 GeV/c incident momentum beam.

Journal Article↗

PubMed2002

Sigma-nucleus potential in A=28.

We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum.

Journal Article↗

PubMed2002

Proton energy spectra in the nonmesonic weak decay of 12lambdaC and 28lambdaSi hypernuclei.

Numbers of protons per Gamma hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of Gamma hypernuclei by the (pi+,K+) reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, Gamma((Lambda)n-->nn)/Gamma((Lambda)p-->np) ( = Gamma(n)/Gamma(p)) were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the Gamma(n)/Gamma(p) ratios are close to 1 both for 12LambdaC and 28LambdaSi in contradiction to theoretical expectations based on meson exchange models.

Journal Article↗

PubMed2001

Observation of a (6)(LambdaLambda)He double hypernucleus.

A double-hyperfragment event has been found in a hybrid-emulsion experiment. It is identified uniquely as the sequential decay of ( 6)(LambdaLambda)He emitted from a Xi(-) hyperon nuclear capture at rest. The mass of ( 6)(LambdaLambda)He and the Lambda-Lambda interaction energy DeltaB(LambdaLambda) have been measured for the first time devoid of the ambiguities due to the possibilities of excited states. The value of DeltaB(LambdaLambda) is 1.01+/-0.20(+0.18)(-0.11) MeV. This demonstrates that the Lambda-Lambda interaction is weakly attractive.

Journal Article↗

PubMed2001

Observation of spin-orbit splitting in lambda single-particle states.

The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. The 13C(K-,pi(-))(13)(Lambda)C reaction was used to excite both the 1/2(-) and 3/2(-) states simultaneously, which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from the states to the ground state were measured in coincidence with the pi(-)'s, by which ls splitting was found to be 152+/-54(stat)+/-36(syst) keV. The value is 20-30 times smaller than exhibited by the ls splitting in the nuclear shell model. This value gives us new insight into the YN interaction.

Journal Article↗

PubMed2001

Measurement of the B(e2) of (7)(lambda)Li and shrinkage of the hypernuclear size.

We report on the first measurement of a hypernuclear gamma-transition probability. gamma rays emitted in the E2(5/2(+)-->1/2(+)) transition of (7)(Lambda)Li were detected by a large-acceptance germanium detector array (Hyperball), and the lifetime of the parent state ( 5/2(+)) was determined by the Doppler shift attenuation method. The obtained result, 5.8(+0.9)(-0.7)+/-0.7 ps, was then converted into the reduced transition probability [ B(E2)] to be B(E2;5/2(+)-->1/2(+)) = 3.6+/-0.5(+0.5)(-0.4) e(2) fm(4). Compared with the B(E2) of the corresponding E2(3(+)-->1(+)) transition in the 6Li nucleus, our result gives evidence that the size of the 6Li core in (7)(Lambda)Li is smaller than the 6Li nucleus in the free space.

Journal Article↗

PubMed2001

Metastases to the penis from carcinoma of the prostate.

A 58-year-old man presented with dysuria at the Osaka Medical College Hospital in November 1996. Laboratory examination revealed elevated serum prostate-specific antigen (PSA) to > 100 ng/mL. Adenocarcinoma of the prostate with metastasis to the bone was diagnosed after a biopsy of the prostate and bone scintigraphy; hormonal therapy was administered. Although bone metastasis was well controlled and the serum PSA level declined to within normal levels (2.0 ng/mL), several painless nodules were found on the penile glans. Biopsy of the nodules showed that the penile tumor was a metastasis from the prostate cancer. The patient underwent partial penectomy for relief from penile pain. The serum PSA level showed no elevation 3 months after the partial penectomy, suggesting that careful observation of prostate cancer patients is necessary, even when oseous metastasis is well controlled and serum PSA levels are kept within normal ranges by hormonal therapy. The case also indicates that urologists should consider the possibility of metastasis to the penis from prostate cancer.

Adenocarcinoma↗

PubMed2000

Observation of a spin-flip M1 transition in 7(lambda)Li.

Using a large-acceptance germanium detector array (Hyperball), we have observed a spin-flip M1 gamma transition between the ground-state spin doublet of (7)(Lambda)Li (3/2(+)-->1/2(+)). The observed energy of 691.7+/-0.6(stat)+/-1.0(syst) keV provides crucial information on the strength of the spin-spin interaction between a Lambda and a nucleon. This is the first observation of well-identified hypernuclear gamma transitions using germanium detectors.

Journal Article↗

PubMed2000

Asymmetry in the nonmesonic weak decay of polarized (5)(Lambda)He hypernuclei

We have measured the asymmetric emission of protons from the nonmesonic decay of polarized (5)(Lambda)He produced by the (pi(+), K+) reaction. (5)(Lambda)He is an s-shell hypernucleus and its polarization is due to the Lambda. One expects to obtain direct information on the elementary weak Lambda-->p-->np process. The asymmetry parameter has been determined to be 0.24+/-0.22. The implication of the result is discussed.

Journal Article↗

PubMed1998

[Epidermoid cyst of the scrotum: a case report].

A 52-year-old male visited our department for a painless swelling from the right side of the anus to the right scrotum that he first noticed 5 years earlier. Palpation revealed a small fist-sized elastic solid mass with a smooth surface from the central area to the inferior pole of the right scrotum. This mass was clearly demarcated from the contents of the scrotum and not adherent to the scrotal skin. A diagnosis of a tumorous lesion in the scrotum was made, and the tumor was resected. Histopathological examination demonstrated a scrotal epidermoid cyst. To our knowledge, this is the 17th case reported in Japan.

Epidermal Cyst↗

PubMed1998

[Idiopathic adrenal hemorrhage: a case report].

A 77-year-old man with a low grade fever persisting for 30 days consulted a local physician. A computed tomographic scan of the abdomen showed a mixed density mass on the left adrenal gland. He was referred to our hospital for further examination. Hormonal assay demonstrated a slightly high level of noradrenalin in the serum (18 pg/ml) and vanillyl mandelic acid in the urine (6.2 ng/ml). Magnetic resonance imaging revealed a heterogeneous mass lesion 3 cm in diameter with a high signal intensity on both T1 and T2 weighted images. Angiography showed a hypovascular mass in the supra-renal region suggesting an adrenal tumor or malignancy. Left adrenalectomy combined with en bloc nephrectomy was performed because of severe adhesion. Histologic evaluation showed hematoma without malignant cells due to idiopathic adrenal hemorrhage.

Adrenal Gland Diseases↗

PubMed1996