Small PMT design. ! Design Concept! Design Implementa6on! On site test report! Engineering Array Test Plan! Design status

Transcription

1 Small PMT design C. Morello for the Torino group! Design Concept! Design Implementa6on! On site test report! Engineering Array Test Plan! Design status 1

2 Design Concept Extension of the WCD dynamic range up to 21 bit (GAP ; M. Roth, Shower universality: comments on anisotropy and satura6on, Lisbon 2013; Auger North Design)! Overcome the XP1805 satura6on problems (40% of saturated events above 50 EeV)! Par6cle density measurements up to few hundred meters from the shower core Addi6on of a small photomul6plier (SPMT) to the WCD with an ac6ve cathode area 60 6mes lower wrt to the exis6ng large PMTs and not requiring significant modifica6ons to the WCD. Integra6on of a 4th PMT in the upgraded electronics without ad- hoc developments of electronics or mechanics modifica6on of the tank. 2

3 Design Implementa6on: choice of the SPMT! Diameter: mechanical compa6bility with the exis6ng 30 mm spare LED window! Photocathode ac6ve area: a simple down- scaling of the SPMT light collec6ng area with respect to the XP1805 PMTs directly results in an extension of the tank dynamic range (if G spmt G xp1805 )! Linearity: maximum NON LINEARITY of - 5 % for I anode 50 ma as for XP1805 SPMT candidates: Hamamatsu R6094 (28 mm diameter), R8619 (25 mm diameter), ET Enterprise 9107B (28 mm diameter) A xp1805 /A R6094,9107B 75 A xp1805 /A R

4 Design Implementa6on: SPMT on the tank LED window SPMT window Posi6on of the SPMT in the tank: LED window 60 cm from the center of the liner. Side LED window easily reachable from hatch cover n. 1. 4

5 Design Implementa6on: SPMT divider SPMT divider: purely resis6ve with progressive voltage ra6o on the last stages for best linearity. R6094, 9107B R8619 Base protected by HV insula6ng lacquer No pogng SPMT with socket for the EA. HV external to the base on a dedicated box (see later) Dividers prototyped by the Torino INFN Electronic Lab. and finalized in IPN- Orsay for the Engineering Array. C.Morello PAO SDEU Cri2cal Design Review - February

6 Results of linearity tests performed in laboratory Hamamatsu S/N Glass Diameter [mm] Photocathode diameter [mm] Heigth [mm] R8619 RU R8619 RS R8619 RW R8619 RW R6094 RJ R6094 RJ R6094 RJ ET Enterprise 9107B B B I anode [ma] N.L. - 5% G HV 1000 V 6

7 Design Implementa6on: SPMT mechanical assembly LED window SPMT base Mechanical assembly compa6ble with all the SPMT models considered for the upgrade 7

8 SPMT high voltage power supply DC- DC converter: SENS- TECH PS2010/12 as for large PMTs CAEN A7501P recently developed Technical SpecificaNons PS2010/12 Sens Tech A7501P CAEN Input Voltage V + 12 V ± 5% Max High Voltage V V Output current V V Vout stability < 0,01 % C - 1 < 60 ppm C - 1 * Output Ripple p- p < 40 mv < 10 mv Output voltage monitor (Vmon) 0 + 4,76 V V * Ouput current monitor (Imon) none 0 + 2,5 V External control voltage (Vset) 0 + 2,44 V 0 + 2,5 V External current control (Iset) none 0 + 2,5 V Power dissipa6on V 375 mw@2000 V * Opera6ng Temperature C C 8

9 HV Temperature cycling C Sens Tech PS2010/12 vs CAEN A7501P (GAP note coming soon) C.Morello PAO SDEU Cri2cal Design Review - February

10 SPMT high voltage power supply 10

11 SPMT connec6ons Circuit to interface the SPMT HV box to the UUB (already used for XP1805). DC- DC converter PS2010/12 or A7501P Slow control 11

12 On site performance tests on DIDI tank SPMT calibra6on procedure 1 Standard tank calibra6on to get the VEM value on XP VEM reproduc6on on XP1805 using the LEDs 3 Using LEDs set the SPMT gain for a given charge ra6o between SPMT and XP1805 to get the super- posi6on of the two linear ranges 4 Check the charge ra6o using real events ( 2 hours of data taking) Cross calibra6on of the SPMT with the average of the 3 XP1805 outputs on DIDI tank. XP1805 saturated events are excluded by the fit. 12

13 On site performance tests on DIDI tank Hamamatsu PMTs R6095 and R8619 installed on the DIDI tank for performance and stability tests. G SPMT 2 3 G XP1805 Log N XP1805 anode average SPMT R6095 Log N XP1805 anode average SPMT R8629 R6095: Charge spectrum of the DIDI tank R8619: Charge spectrum of the DIDI tank The spectra show the overlapping linear region with the XP1805, the XP1805 satura6on and the extension of the WCD linear range obtained with the SPMT. 13

14 On site performance tests on DIDI tank (real events) R6095 RMS 6% R8619 RMS 4% Let panels: average VEM (R6095) and charge ra6o (R8619) between the large and small PMTs for local showers triggering the tank. Right panels: rela6ve distribu6on of the PMT charge ra6os (R VEM i = Q XP1805 i / Q SPMT ) 14

15 On site performance tests on DIDI tank (LED events) R6095 RMS 4% Test performed using the LED system every 30 minutes for 6 days. The relanve fluctuanon of the rano Ri LED = Qi XP1805 / Q SPMT is of the order of 4 % in agreement with the results obtained using real events. Rela6ve distribu6on of the PMTs charge ra6o Ri LED = using ar6ficial light pulses. 15

16 On site performance tests on DIDI tank (linearity check) The linear range of the SPMT can be controlled by the LED flasher powered by + 20 V as implemented in the new UUB. 16

17 Engineering Array Test Plan! Qualify the selected SPMT models and bases for the final produc6on: few tanks for each of the selected models;! Validate on site the use of the CAEN A7501 dc- dc converter;! Validate on site the SPMT mechanical assembly (design compa6ble with all selected SPMT);! Check and improve the cross calibra6on XP SPMT 7 SPMT prototypes are ready for the Engineering Array 17

18 Design Status! The design of the SPMT mechanics, high voltage and readout electronics is defined.! 7 first prototypes are ready.! The on site tests show all performance specifica6ons are met.! The extension of the Surface Detector dynamic range with the Small PMT is expected to be at least of a factor of 32, promising insight into the physics of Cosmic Ray showers close to the core. M.Agliexa et al., Small PMT A proposal to extend the dynamic range of the Auger SD for opera6ons beyond 2015, GAP M.Agliexa et al., Small PMT Status report, GAP M.Agliexa et al., Small PMT Upgrade Project: status report for the Engineering array, GAP

19 C.Morello PAO SDEU Cri6cal Design Review - February

20 Design Implementa6on: SPMT divider 20

21 Design Implementa6on: SPMT divider 21