1. Prototype production and test
Ionization Chamber
Prototype production and test
채경육
성균관대학교 물리학과

2. Usage Stage 1 after the reaction target chamber
- to detect heavy recoils
(blocker)
- to normalize beam
currents F1
In-flight separation or
Beam transport F0 F2 WF
Stage 2 F3
Q-Q-WF-D
(VAMOS-like
spectrometer)
at the end of KOBRA
- beam current normalization
- heavy recoils (after rejection) F4 F4

3. Conventional design • Long life using gas flowing system
• Relatively easy to make and use
• Easy to fabricate large area detectors
• Reasonable energy resolution
• Slow response
→ new design is required
• beam current normalization
• beam composition monitoring
• detecting heavy recoils

4. New design: tilted electrodes, tilted window
• Fast IC: NIM A 751, 6 (2014)
Portable IC: JKPS 64, 516 (2014)
• tilted window & electrodes
perpendicular
76Ge, 76Se
~700,000 pps

5. Prototype • based on Fast IC design (ORNL)
• distance between adjacent electrodes: 1 cm → Fast response time!
• easy to replace window
• entrance window: gauge 20C Mylar

6. Electrodes • easy to replace window • entrance window: gauge 20C Mylar
• electrodes: Cu frames " gold coated tungsten wires
• wire pitch: 2 mm (transmission rate ~99%)
• cathodes are combined and grounded
• each anode is connected to a BNC feedthrough

7. Results • 241Am source • proton beams from MC-50 cyclotron
• (13%), (85%) MeV
• Energy resolution: 6.3%
• proton beams from MC-50 cyclotron
• will be commissioned in July
• protons scattered from carbon

9. Electronics preamp: Canberra Model 2004 amp: Canberra Model 2020 ADC
unipolar
ADC
preamp
amp
CFD
bipolar
strobe

10. Pictures

11. Results I - 10B beam, Ebeam = 60 MeV
50 kHz
200 kHz
300 kHz
Beam particles stopping at the wire
• new fast ion counter can reliably count up to 300,000 pps
• transmission rate through a plane of electrode is ~98% for 1mm spacing
• a set of electrodes with 2mm pitch was made

12. Results II – cocktail beams
76Ge, 76Se
80Ge, 80Se
~400,000 pps
~33,000 pps