PPAC production and status Kwangbok Lee Low Energy Nuclear Science team Rare Isotope Science Project Institute for Basic Science July 11,

CVS repository for simulation setup.  Now we has codes for PPAC and I.C. Welcome to check and update it and more welcome to upload your code!  Create username at and your id will be added as collaborator and visit to see the codes.  For download from CVS repository to your NRICH directory : 1. Create directory 2. Move to the directory and type svn co 3. This will create two directories of branches and trunk.  For add your file to CVS repository : svn add file (or directory) at the trunk directory. : svn commit -m “leave your message for the adding” file (or directory)  For update from NRHICH to CVS repository : svn commit -m “leave your message for the code update” file (or directory)  For update from CVS repository to NRHICH : svn update files (or directory) 2

Electrode evaporation at Nanofam Ag evaporation on Cathode Ag evaporation on Anode Dahee and Dr. Moon Zoomed in 4 cathodes and 2 anode have been evaporated. 3

First assembly Strip number 1 (x strips) Strip number 42 Strip number 1 Strip number 42 Right view Left view X1 X2 Y1 Y2 SIG. HV (y strips) chip #3 chip #9 Successful assembly by myself, Mr. Kim and dahee on 16, 17 and 18 June at KIGAM ! * KIGAM (Korea Institute of Geoscience and Mineral Resources) 4

Assembly issues Tried o-ring and silicon tube for contacting electrodes to PCB. PCB gets bent by pressure at the edges. Attach with silicon tubeAttach with o-ring Only one side of anode is evaporated by silver, which means avalanche electrons of other side has no way to get through -> can distort electric field and signal. 5

Delay line test to check signal loss  Condition single pulse; amplitude, ±25 mV width, 100ns signal freq., 1 pulse/sec. impedance matching; 50 Ω negative input X1, X2 positive input X1, X2 Pulse is near X1Pulse is in the middle of X1 and X2 6

GEANT4 simulation for PPAC Most of energy loss is from mylar layer. Low energy beam would be stopped with current 2 μm mylars. (-> 1 μm mylar) -> Mylar layer thickness would be critical issue to reduce the energy loss. 15 O, 5 A MeV 15 O, 1 A MeV MeV E loss /u in 5 mylar layers E loss /u in gas of gap E loss /u in 5 mylar layers E loss /u in gas of gap Mean: MeV Mean: MeV Mean: MeVMean: MeV 7

PPAC GARFIELD simulation 800 V 1300 V α, 5.64 MeV ns Anode Cathode 4 mm fC/ns Avalanche shape field distribution To understand the avalanche behavior, other properties in the gas. C 3 F 8 (perfluoropropane), 10 torr C 3 F 8 (perfluoropropane), 30 torr α, 56.4 MeV ns fC/ns 8

PPAC arrangement for test 9

bi2 Gas control system 10 Gas bomb1 Regulator Line Regulator Flow Control Bypass PT IN OUT Reservoir Tank Dry PumpRotary Pump PPAC-1 Vacuum Chamber PPAC-2 10

Gas control system at RIKEN 11

BACK UP 12

Item to check for next assembly  PCB can be thicker as 1.6 t -> 2.0 or 3.0 t (should be careful as it can disturb vacuuming and break the mylar window)  Change PCB connector as angle type - Consider other connector, not Mdex connector - Consider connector for HV  HV register can have 2 or 3 W (proto type has 1/4W, 2.2M -> can handle 0.34mA)  PCB needs another hole for keeping stable gap size.  Epoxy should not be too much especially near the pad or strip.  Consider material between the PCB board to attach electrode to PCB strip ex. silicon tube, rectangular shape. proto type uses 3.5 mm silicon tube for 2.4 mm space. 5.0 mm for 4 mm space  Check if preamp can handle DC 800 ~ 1000V.  Use myeonbong for epoxy  Better to have clean bench (400 M won) - better than the clean room as we can do soldering work. Note:  Anode PCB ground is floating.  Register measurement with multi-meter shows ~ 15 Ω (pad), 20 Ω (strip) while multi-meter has 5 Ω, which means they have register ~ 10 and 15 Ω, respectively. 13