Open-loop correction for an eddy current dominated beam-switching magnet.

A beam-switching magnet and the pulsed power supply it requires have been developed for the Japan Proton Accelerator Research Complex. To switch bunched proton beams, the dipole magnetic field must reach its maximum value within 40 ms. In addition, the field flatness should be less than 5 × 10(-4) to guide each bunched beam to the designed orbit. From a magnetic field measurement by using a long search coil, it was found that an eddy current in the thick endplates and laminated core disturbs the rise of the magnetic field. The eddy current also deteriorates the field flatness over the required flat-top period. The measured field flatness was 5 × 10(-3). By using a double-exponential equation to approximate the measured magnetic field, a compensation pattern for the eddy current was calculated. The integrated magnetic field was measured while using the newly developed open-loop compensation system. A field flatness of less than 5 × 10(-4), which is an acceptable value, was achieved.

U-shape rotating anti-cathode compact X-ray generator: 20 times stronger than the commercially available X-ray source.

A new type of U-shape anti-cathode X-ray generator in which the inner surface of a cylindrical target is irradiated by an electron beam has been made by modifying a conventional rotating anti-cathode X-ray generator whose brightness in the catalog is 12 kW mm(-2). The target material (Cu), target radius (50 mm) and rotating speed (6,000 r.p.m.) were not changed in this modification. A brightness of 52 kW mm(-2) was obtained by this U-shape-type X-ray generator. This means that the brightness of the new type is 4.3 times greater than that of the old unmodified one. Furthermore, the new-type X-ray generator yielded a brightness of 129 kW mm(-2) by adding a carbon coating on the Cu target. This means an overall increase of brightness of ten times. The original generator has the highest brightness in the generators of the same class (having a radius of 50 mm and rotation speed of 6,000 r.p.m.). Observations showed that Cu Kα counts at vertical incidence of the electron beam onto the surface of the new target, which is initially optically smooth, decrease as the surface is roughened by a severe thermal stress caused by strong electron beam exposure. Further observation reveals, however, that oblique incidence of the electron beam onto the roughened surface drastically increased the X-ray output and amounts to twice as much as that from a smooth surface at vertical incidence. Thus, at the present stage, an overall increase of brightness has been realised at a level 20 times stronger than that of the original commercially offered X-ray generator that we modified.

Highly bright X-ray generator using heat of fusion with a specially designed rotating anticathode.

A new type of rotating anticathode X-ray generator has been developed, in which the electron beam irradiates the inner surface of a U-shaped anticathode (Cu). A high-flux electron beam is focused on the inner surface by optimizing the shape of the bending magnet. The power of the electron beam can be increased to the point at which the irradiated part of the inner surface is melted, because a strong centrifugal force fixes the melted part on the inner surface. When the irradiated part is melted, a large amount of energy is stored as the heat of fusion, resulting in emission of X-rays 4.3 times more brilliant than can be attained by a conventional rotating anticathode. Oscillating translation of the irradiated position on the inner surface during use is expected to be very advantageous for extending the target life. A carbon film coating on the inner surface is considered to suppress evaporation of the target metal and will be an important technique in further realization of highly bright X-ray generation.

Beam-beam limit in e+e- circular colliders.

Beam-beam effects limit the luminosity of circular colliders. Once the bunch population exceeds a threshold, the luminosity increases at a slower rate. This phenomenon is called the beam-beam limit. Onset of the beam-beam limit has been analyzed with various simulation methods based on the weak-strong and strong-strong models. We have observed that an incoherent phenomenon is mainly concerned in the beam-beam limit. The simulation have shown that equilibrium distributions of the two colliding beams are distorted from Gaussians when the luminosity is limited. The beam-beam limit is estimated to be xi approximately 0.1 for a B factory with damping time of several thousand turns.

[A case of renal pelvic tumor with heterotopic bone formation].

The patient was a 74-year-old man who was referred to our hospital with a complaint of left flank pain. Laboratory data were almost within normal limits and urine cytology was positive. X-ray examination revealed a calcification in the left kidney and abdominal CT scan confirmed the presence of a heterogenous renal pelvic mass which contained a calcification. Based on these examinations, a diagnosis of a renal pelvic cancer with heterotopic bone formation was made. Subsequently, left nephroureterectomy was performed. Grossly, the renal pelvis of the resected kidney was filled with a mass which had a white cut surface and bone-like tendency. Histopathologically, a poorly differentiated transitional cell carcinoma with massive bone formation was found. Fifty five cases of heterotopic bone formation in the kidney have been reported in Japan. Among the cases, 4 cases were complicated with renal pelvic tumor and our case was the second case of heterotopic bone formation complicated with a transitional cell carcinoma of the renal pelvis in Japan.

[Two cases of nephrogenic adenoma in the bladder diverticulum].

We report two cases of a nephrogenic adenoma in the bladder diverticulum. The first patient was an 81-year-old man with gross hematuria. Cystoscopy revealed bladder diverticulum and a papillary tumor within. Bladder diverticulectomy was performed and the histopathological diagnosis was a nephrogenic adenoma. The second patient was a 50-year-old man with gross hematuria and dysuria. Transabdominal ultrasound revealed bladder diverticulum. Transurethral coagulation of the bladder diverticulum was performed. Then three papillary tumors were detected, and were resected transurethrally. The histopathological diagnosis was a nephrogenic adenoma. These are the first and second cases of a nephrogenic adenoma in the bladder diverticulum reported in Japan.

[Intra-arterial infusion chemotherapy for liver metastases of testicular tumors: report of two cases].

Two cases of testicular tumors with lymph node involvement and multiple lung and liver metastases were treated successfully with intra-arterial infusion chemotherapy. Case 1: A 30-year-old man presented with right scrotal swelling and an abdominal mass. He had a large retroperitoneal mass and multiple lung and liver metastases on computed tomographic (CT) scan and chest X-ray. Right inguinal orchiectomy was performed. Histopathological diagnosis revealed embryonal cell carcinoma and choriocarcinoma. Cisplatin, vinblastine, VP-16 and pepleomycin combination chemotherapy (PVeBV) was started and repeated for 2 courses. The retroperitoneal mass and lung tumors decreased in size, but liver tumors enlarged. Systemic and intrahepatic arterial infusion combined with chemotherapy was administered, and intra-arterial chemotherapy (cisplatin, VP-16) was added. The patient also received systemic chemotherapy (carboplatin, VP-16, ifosfamide). After chemotherapy, retroperitoneal lymph node dissection was performed. Microscopic examination revealed no viable cancer cells. On CT scan, no retroperitoneal, liver, or lung tumor was detected. Case 2: A 43-year-old man presented with right scrotal swelling and an abdominal mass. CT scan revealed a large retroperitoneal mass as well as lung and multiple liver metastases. Right inguinal orchiectomy was performed. Histopathological diagnosis revealed seminoma. Cisplatin, vinblastine, VP-16 and pepleomycin combination chemotherapy (PVeBV) was administered, but the liver tumors ware enlarged on CT scan. Intrahepatic arterial infusion chemotherapy (cisplatin, VP-16) was started and repeated for 4 courses. On CT scan, the lung metastasis seemed to have disappeared, and the retroperitoneal mass and liver metastases were decreased in size.