photocathode characteristics spectral range : 290-650 nm maximum sensitivity at : 420 nm sensitivity ? : luminous : 70 a/lm ? blue : min : 7.5 typ : 10 a/lmf radiant, at 420 nm : typ : 80 ma/w characteristics with voltage divider a gain slope (vs supp. volt., log/log) 9 for a gain of : 3 x 10 7 ? supply voltage : max: 2600 typ: 2000 v min : 1750 ? anode dark current ? : max: 100 typ : 10 na ? background noise ? : max : 2500 typ: 900 c/s single electron spectrum ? : resolution typ: 70 % peak to valley ratio typ. 2.5 pulse amplitude resolution for 137 cs ? : 7.2 % gain halved for a magnetic field of : perpendicular to axis "n" : 0.15 mt parallel with axis "n" : 0.12 mt characteristics with voltage divider c ? : c b a for a supply voltage of 2500 2800 2000 v gain 4.0 x 10 7 4.0 x 10 6 3.0 x 10 7 linearity (2%) of an. current up to : 70 280 25 ma anode pulse ? rise time : 1.5 1.7 1.6 ns duration at half height : 2.4 2.7 3.7 ns transit time 30 31 28 ns transit time spread standard deviation : .25 ns capacitances anode to all 7 pf grid to k + d1 + d5 : 20 pf photomultiplier tubes XP2020 product specification page 1/3 08/09/98 abcde applications : high and medium energy physics where the number of photons to be detected is very low and where utmost time characteristics are required. this tube features a good linearity, a very low background noise and extremely good time characteristics and good single electron spectrum description : window : material : borosilicate glass photocathode : bi-alkali refr. index at 420 nm : 1.48 multiplier : structure : linear focused nb of stages : 12 mass : 240 g standard very fast, 12-stage, 51 mm (2") round tube
recommended voltage divider type a for maximum gain k g d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11 d12 a 1.2 2.8 1.2 1.8 1 1 1 1 1 1 1 1 1 1 (total :17) type b for best timing / linearity compromise k g d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11 d12 a 1.2 2.8 1.2 1.8 1 1.25 1.5 1.5 1.75 2.5 3.5 4.5 8 10 (total :42.5) type c for timing/ linearity / gain compromise k g d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11 d12 a 1.2 2.8 1.2 1.8 1 1 1 1 1 1 1.5 1.5 3 2.5 (total :21.5) k : photocathode g : focusing electrode dn : dynode a : anode limiting values gain : max : 2.0 x 10 8 supply voltage : max : 3000 v continuous anode current : max : 0.2 ma voltage between g and photocathode : max : 300 v first dynode and pk : min : 210 max : 800 v consecutive dynodes (except 11&12) : max : 400 v dynodes d11 and d12 : max : 600 v anode and last dynode : min : 80 max : 700 v ambient temperature short operation (< 30 mn) : min : -30 max : +80 c continuous operation & storage : min : -30 max : +50 c photomultiplier tubes XP2020 product specification page 2/3 08/09/98 abcde notes t characteristic measured and mentioned on the test ticket of each tube. ? luminous sensitivity is measured with a tungsten filament lamp with a colour temperature of 2856 5 k. the blue sensitivity, expressed in a/lmf ("f" as in filtered) is measured with a tungsten filament lamp with a color temperature of 2856 . 5 k. light is transmitted through a blue filter corning cs no.5-58, polished to half stock thickness. the radiant sensitivity is measured with a tungsten filament lamp with a colour temperature of 2856 5k. light is transmitted throught an interference filter. radiant sensitivity at 420 nm, expressed in ma/w, can be estimated by multiplying the blue sensitivity, expressed in a/lmf, by 7.5 for this type of tube. ? dark current is measured at ambient temperature, after the tube has been in darkness for approximatively 1 min. lower value can be obtained after a longer stabilisation period in darkness (approx. 30 min.). ? noise is measured at ambiant temperature, after the tube has been stored with its protection hood, the tube is placed in darkness with vd set at a value to give a gain of 3 x 10 7 . after a 30 mn stabilisation period, noise pulses with a threshold of 1 pc (corresponding to 0.2 pe) are recorded. ? the peak to valley ratio is defined as the single el e ctron peak value divided by the minimum value at the left of the peak. ? pulse amplitude resolution for 137 cs is measured with nai(tl) cylindrical scintillator with a diameter of 51 mm and a height of 51 mm. the count rate used is ~ 1.0 x 10 4 c/s. ? to obtain a peak pulse current greater than that obtainable with divider a, it is necessary to increase the inter-dynode voltage progressively. divider circuit c is an example of a progressive divider, giving a compromise between gain, speed and linearity. other dividers can be conceived to achieve other compromises. it is generally recommended that the voltage ratio between two successive stages is less than 2. ? measured with a pulse light source, with a pulse duration (fwhm) of approximately 1 ns., the cathode being completely illuminated. the rise time is determined between 10 % and 90 % of the anode pulse amplitude. the signal transit time is measured between the instant at which the illuminating pulse of the cathode becomes maximum, and the instant at which the anode pulse reaches its maximum. rise time, pulse duration and transit time vary with respect to high tension supply voltage vht as (vht)-?. note : the enveloppe of the tube is covered witha conductive coating connected to the photocathode on top of which a black paint is applied. this paint is neither guaranteed to be light-tight nor electrically insulating. care should be taken to avoid electrical shock.
photomultiplier tubes XP2020 product specification page 3/3 08/09/98 abcde ref. 66100004 sp : short pin nc : not connected ic : internal connection n : plane of symetry of the multiplier k : cathode dn : dynode a : anode ct : coating XP2020 200 300 400 500 600 700 800 1 10 100 wavelength (nm) sk (ma/w) accessories socket : fe1120 mu-metal shield : ms172 voltage divider : vd124k typical spectral characteritics XP2020 1000 1500 2000 2500 3000 1e+4 1e+5 1e+6 1e+7 1e+8 vht(v) gain a c b typical gain curve
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