Recent ucsc_physics_st items

IRIS: AN INTENSE RADIATION INTEGRATION SENSOR FOR TERRESTRIAL GAMMA-RAY FLASHES

Thu, 5 Dec 2024 00:00:00 +0000

Terrestrial Gamma-ray flashes (TGFs) are energetic flashes of gamma-rays produced by lightning in thunderstorms. The levels of radioactivity and effects that TGFs have on people and aircraft in close proximity to lightning are still unknown. Current TGF detectors have proven to paralyze and oversaturate when in close proximity to bright TGFs. Because of this, the Intense Radiation Integration Sensor (IRIS) was developed to detect TGFs at close range without saturation, using two photodiodes (bare and with scintillator attached) to detect incoming relativistic Compton electrons from the bremsstrahlung TGF gamma-rays. IRIS was developed at the Santa Cruz Institute of Particle Physics (SCIPP) in Santa Cruz, California and field tested using a Mobetron electron-beam accelerator at the MD Anderson Cancer Center in Houston, Texas. Field testing showed IRIS’s sensitivity levels to be higher than we ultimately wanted, warranting next steps in IRIS development to use four bare photodiodes...

An Investigation of Depletion in AstroPix, a High Voltage Monolithic CMOS Sensor

Wed, 11 Sep 2024 00:00:00 +0000

Future space based particle physics experiments require detectors to be low power to ensure efficiency where no large amounts of energy can be continuously provided. The AstroPix chip aims for a power consumption of 1.5mW/cm2 and energy resolution of 2% at600keV per sensor. To determine the readiness of several wafers of different resistivities, 3 experiments were conducted. CV and IV data were taken using a probe station in SCIPP’s electronics room. The results determined that while the IV relationship looked normal for sensors with lower resistivities (from wafers 2 and 6), the sensors with higher resistivities (from wafers 10 and 11) had much higher current than anticipated, which inhibited the use of high voltage as breakdown occurred early.

Another experiment consisted of taking data from a laser edge-TCT scan; this test confirmed the strange behavior of high resistivity chips as voltage amplitude pulses losttheir shape and amplitude with higher bias voltages which...