José Repond Argonne National Laboratory DHCAL Developments José Repond Argonne National Laboratory CALICE Collaboration Meeting Max-Planck-Institute, München, Germany September 9 – 11, 2015 Go to ”Insert (View) | Header and Footer" to add your organization, sponsor, meeting name here; then, click "Apply to All"

A) 1-glass RPC validated Resistive paint Signal pads Mylar Aluminum foil 1.1mm glass 1.2mm gas gap -HV A) 1-glass RPC validated Measurements with Test Beam Rate capability better than 2-glass Pad multiplicity close to 1 Chambers work in showers Measurements with Cosmic Rays Published in JINST 10 (2015) P05003

B) Measurement of the rate capability Three different RPC designs 1) Standard 2-glass design (20x 20 cm2) 2) 1-glass design (23 x 48 cm2) 3) 2-glass design with semi-conductive glass (20 x20 cm2) Glass Model S8900 from Schott Glass Technologies Inc. Readout Standard DHCAL readout (1-bit) Data taking with external trigger (finger counters) Set-up in beam 2 chambers for each design (6 in total) Spaced about 5 cm apart RPC design Number of glass plates Area A [cm2] Bulk resistivity ρ [Ωcm] Total thickness t of the glass [cm] Conductance per area of the glass G =( ρ·t)-1 [Ω-1cm-2 ] 1 2 400 4.7 × 1012 0.22 1.0 × 10-12 1536 3.7 × 1012 0.11 2.4 × 10-12 3 6.3 × 1010 0.28 5.6 × 10-11

Measurement in Fermilab Test Beam Efficiency/pad multiplicity versus beam intensity [Hz/cm2] Beam 120 GeV protons Defocused to provide larger beam spot: 2σx × 2σy = 2.0 × 1.6 cm2 Intensity varied from 10 to 113,800 Hz/cm2 Beam extraction not uniform over spill at low intensities, much better at high intensities Systematic uncertainty in beam intensity from extraction (dominant) and beam spot

Results I Comments As expected, with decrease in efficiency with increasing rate 1-glass design better than standard RPC Semi-conductive chamber better than 1-glass design Pad multiplicity close to unity for 1-glass design Pad multiplicity high for semi-conductive chamber (thicker glass)

Results II Determine Rate I50% at which RPC 50% efficient Compare different designs Fit to empirical function I50% = a + bH + cH3 with H = 1/log10(G) Extrapolate to 1 1.1 mm semi-conductive glass RPC → I50% ~ 25kHz/cm2 arXiv: 1507.06968: Submitted to JINST

Future DHCAL Activities Funding for the DHCAL Has been terminated on October 1, 2015 Future activities Plan to perform detailed, analog measurements of the signal charge Still working on publishing results from test beam runs