Same geometry, but different size of the rim RUI: SAME WEIZMANN GEOMETRY WEIZMANN With rim PARAMETERS: Diameter = 0.3 mm Pitch= 0.7 mm Thickness = 0.4 mm Gas: Ar/CO2 – 70/30 Without rim RUI: WITHOUT POLISHING RUI:CHEMICALLY POLISHED THGEM: same geometry

Before and after the chemical polishing REMARKS: different aspects of the rim after the two different treatments! THGEM: same geometry

THGEM: Electro-chemical polished PARAMETERS: Diameter = 0.3 mm Pitch= 0.7 mm Thickness = 0.4 mm Rim = 0 mm Gas: Ar/CO2 – 70/30 GEOMETRICAL CONFIGURATION THGEM DRIFT ANODE Thickness 6.5 mm 5mm A picture taken by the microscope: it’s to remark the rim after the electro-chemical polishing. For a best quantification of the rim it’s convenient to cut and to observe the cross-section avoiding the optics effects present in the current picture. THGEM electro-chemical polished

Current measurement setup Back view of the picoamperometer Glass box – N2 is flushing input HV source Triaxial cable floating REMARKS: it’s not visible, but there’s an internal connection (“meter-connection”) in the black “HV input” activated by selection on the picoamperometer before starting the measurement Grounded to CERN ground

Current measurement (behaviour) ∆V= 1KV applied to the electrodes THGEM electro-chemical polished

Current measurement (total data) First 2 values ~ 2nA During the initial 30 seconds there are some fluctuations maybe due to the stabilization of the voltage on the instrument and/or some external causes which perturbed the measurement (very sensitive to the movements around the setup) THGEM electro-chemical polished

Induction scan & its energy resolution Working conditions: Edrift=2 KV/cm ∆V=1.475 KV THGEM electro-chemical polished

Drift scan & its energy resolution Working conditions: Einduction=3 KV/cm ∆V=1.475 KV THGEM electro-chemical polished

Strange behaviour for the energy resolution Working conditions: Einduction=3 KV/cm ∆V=1.475 KV THGEM electro-chemical polished

Scan voltage and rate capability Einduction=3.5 KV/cm; Edrift=1.5 KV/cm ∆V=1.475 KV Source collimated 1.Voltage Scan 2.Rate capability THGEM electro-chemical polished

THGEM electro-chemical polished Gain estimation ∆V=1.475 KV, G~1550 ∆V=1.45 KV, G~950 ∆V=1.425 KV, G~590 ∆V=1.4 KV, G~360 ∆V=1.375 KV, G~220 Einduction=3.5 KV/cm; Edrift=1.5 KV/cm Source collimated THGEM electro-chemical polished

THGEM electro-chemical polished Time measurement An example of the spectrum acquired pedestal Pulse test Some problems with the fit (black spikes) Possible explanation: variation of the temperature THGEM electro-chemical polished

THGEM: kapton multilayers & chromium (103Å thick) NO ELECRICAL CONNECTION  NO CHARACTERIZATION PARAMETERS: Diameter = 0.5 mm Pitch= 0.8 mm Thickness = 0.6 mm Rim = 0 mm Gas: Ar/CO2 – 70/30 Zoom THGEM: kapton substrate chromium layer

THGEM: kapton multilayers & copper (5 μm thick) PARAMETERS: Diameter = 0.5 mm Pitch= 0.8 mm Thickness = 0.6 mm Rim = 0 mm Gas: Ar/CO2 – 70/30 GEOMETRICAL CONFIGURATION THGEM DRIFT ANODE Thickness 6.5 mm 5mm THGEM: kapton substrate 5μm Cu

THGEM: kapton substrate 5μm Cu Current measurement Jumps due to the changing of the range ∆V= 1KV applied to the electrodes THGEM: kapton substrate 5μm Cu

Comparison of 2 spectrum with different source collimation Einduction=3.5 KV/cm; Edrift~1.5 KV/cm ∆V=1.71 KV THGEM: kapton substrate 5μm Cu

THGEM: fibre glass with asymmetric rims side A side B PARAMETERS: Diameter = 0.3 mm Pitch= 0.7 mm Thickness = 0.4 mm RimsideA = 0.1 mm RimsideB = 0.03 mm Gas: Ar/CO2 – 70/30 GEOMETRICAL CONFIGURATION Some garbage THGEM DRIFT ANODE Thickness 6.5 mm 5mm THGEM asymmetric rims

Current measured Voltage on Voltage off and cables disconnected from the instrument Voltage off Voltage off THGEM asymmetric rims

The charging-up movie: reading from the bottom electrode Einduction=4 KV/cm; Edrift~1 KV/cm; ∆V=1.18 KV; Collimated X-Ray source (~ 1 mm of diameter); The smallest rim (30μm) is on the top of the THGEM Local effect next step THGEM submitted to the cleaning procedure done by Rui THGEM asymmetric rims

THGEM: fibre glass without rim PARAMETERS: Diameter = 0.3 mm Pitch= 0.7 mm Thickness = 0.4 mm Rim = 0 mm Gas: Ar/CO2 – 70/30 GEOMETRICAL CONFIGURATION THGEM DRIFT ANODE Thickness 6.5 mm 5mm THGEM without rim

Gain estimation of this THGEM for ∆V=1.35KV is ~300 Rate capability Averaging the current plateau and plotting vs the X-Ray current Gain estimation of this THGEM for ∆V=1.35KV is ~300 THGEM without rim

Induction scan, its energy resolution & comparison with the behaviour of THGEM electro-chem. pol. Edrift~1.5 KV/cm ∆V=1.35 KV Rate= 1.6 KHz Collimated source Gas flux: 5l/h Working conditions Same working conditions except for the gas flow into the chamber of the THGEM electro-chem. polished was higher (8l/h) and the drift field value THGEM without rim

Drift scan, its energy resolution & comparison with the behaviour of THGEM electro-chem. pol. Einduction~3 KV/cm ∆V=1.35 KV Rate= 1.7 KHz Collimated source Gas flux: 5l/h Working conditions Same working conditions except for the gas flow into the chamber of the THGEM electro-chem. polished was higher (8l/h) THGEM without rim

Consistence between pulse height spectra and current measurement always from the anode THGEM without rim

Position scan before and after time stability measurement An example of the spectrum Collimated source 0.2 KHz Same working conditions: Einduction~3.5 KV/cm Edrift~1.5 KV/cm ∆VSTD=1.35 KV ∆VELECTRO=1.45 KV Rate= 0.84 KHz Collimated source THGEM without rim