IBIC2012 - List of Keywords (space-charge)

Paper	Title	Other Keywords	Page
TUPB69	Numerical Analysis on the Gain-reduction Characteristics of Multi-wire Proportional Chambers	ion, simulation, electron, cathode	502
	K. Katagiri, T. Furukawa, K. Noda NIRS, Chiba-shi, Japan
	Several MWPC (Multi-Wire Proportional Chamber) monitors are installed to diagnosis the beam profiles in the high-energy beam transport at HIMAC (Heavy Ion Medical Accelerator in Chiba) synchrotrons. When the intensity of the incident beams are much high, the gain reduction of the output signal from the MWPC monitor occurs due to the space charge effect of positive ions around the anode wires. The gain reduction is expected to be improved by changing geometric parameters, such as anode radius and distance between electrodes. In order to investigate the gain-reduction characteristics for different geometric parameters, we performed numerical simulation using a numerical code. The numerical code was developed using a two-dimensional drift-diffusion model to evaluate the gas gain including the reduction effect caused by the space charge effect of the moving positive ions. We investigate the gain-reduction rate for several parameters of the anode distance when changing the beam intensity. From these results, we discuss desirable distances between the anode wires to improve the gain reduction.

Paper

Title

Other Keywords

Page

TUPB69

Numerical Analysis on the Gain-reduction Characteristics of Multi-wire Proportional Chambers

ion, simulation, electron, cathode

502

K. Katagiri, T. Furukawa, K. Noda
NIRS, Chiba-shi, Japan

Several MWPC (Multi-Wire Proportional Chamber) monitors are installed to diagnosis the beam profiles in the high-energy beam transport at HIMAC (Heavy Ion Medical Accelerator in Chiba) synchrotrons. When the intensity of the incident beams are much high, the gain reduction of the output signal from the MWPC monitor occurs due to the space charge effect of positive ions around the anode wires. The gain reduction is expected to be improved by changing geometric parameters, such as anode radius and distance between electrodes. In order to investigate the gain-reduction characteristics for different geometric parameters, we performed numerical simulation using a numerical code. The numerical code was developed using a two-dimensional drift-diffusion model to evaluate the gas gain including the reduction effect caused by the space charge effect of the moving positive ions. We investigate the gain-reduction rate for several parameters of the anode distance when changing the beam intensity. From these results, we discuss desirable distances between the anode wires to improve the gain reduction.