Characteristics of signals originating near the lithium-diffused N+ contact of high purity germanium p-type point contact detectors

Aguayo, E.; Amman, M.; Avignone, F. T.; Barabash, A. S.; Barton, Paul; Beene, J. R.; Bertrand, F.; Boswell, M.; Brudanin, V.; Busch, M.; Chan, Y. D.; Christofferson, C. D.; Collar, J. I.; Combs, D. C.; Cooper, R. J.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; Esterline, J.; Fast, J. E.; Fields, N.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Gehman, V. M.; Giovanetti, G. K.; Green, M. P.; Guiseppe, V. E.; Gusey, K.; Hallin, A. L.; Hazama, R.; Henning, R.; Hoppe, E. W.; Horton, Mark; Howard, S.; Howe, M. A.; Johnson, Rob; Keeter, K. J.; Kidd, M. F.; Knecht, A.; Kochetov, O.; Коновалов, С. И.; Kouzes, Richard T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; Looker, Quinn; Luke, P.N.; MacMullin, S.; Marino, M. G.; Martin, R. D.; Merriman, J. H.; Miller, Michael L.; Mizouni, L.; Nomachi, M.; Orrell, J. L.; Overman, Nicole; Perumpilly, G.; Phillips, D. G.; Poon, A. W. P.; Radford, D. C.; Rielage, K.; Robertson, R. G. H.; Ronquest, M.; Schubert, A.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Steele, D.; Strain, J.; Timkin, V.; Tornow, W.; Varner, R. L.; Vetter, K.; Vorren, K.; Wilkerson, J. F.; Yakushev, E.; Yaver, H.; Young, A. R.; Yu, C.‐H.; Yumatov, V.

doi:10.1016/j.nima.2012.11.004

Cited by 56 publications

(26 citation statements)

References 32 publications

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“…[47], the difference from the reference the T 2ν 1/2 result is less than 0.1 %. -A possible effect of a transition layer, where it is assumed that the n + dead layer on the detector surfaces is partially active, has been investigated [48,49]. The dead layer thickness for individual detectors assumed in MC simulations was given according to the listed values in Ref.…”

Section: Systematic Uncertaintiesmentioning

confidence: 99%

“…The medium distant position is represented by decays in the radon-shroud or in the LAr, having a probability 1/2 in contrast. -Extensive studies of the characteristics of the BEGe diodes suggest the presence of a transition layer between the region where the detector is fully effi-cient and the external dead region [48,49]. An uncertainty as high as ±0.5 % on the lower limits of T 0νχ 1/2 is estimated for this effect in the case of the BEGe detectors.…”

Section: (I) Detector Parameters and Fit Modelmentioning

confidence: 99%

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Results on $$\beta \beta $$ β β decay with emission of two neutrinos or Majorons in $$^{76}$$ 76 Ge from GERDA Phase I

Agostini¹,

Allardt²,

Bakalyarov³

et al. 2015

Eur. Phys. J. C

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A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed a e-mail: gerda-eb@mpi-hd.mpg.de using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with 123 416 Page 2 of 12 Eur. Phys. J. C (2015) 75 :416 spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 10 23 yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with 76 Ge. A new result for the half-life of the neutrino-accompanied ββ decay of 76 Ge with significantly reduced uncertainties is also given, resulting in T 2ν 1/2 = (1.926 ± 0.094) × 10 21 yr.

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Section: Systematic Uncertaintiesmentioning

confidence: 99%

Section: (I) Detector Parameters and Fit Modelmentioning

confidence: 99%

Results on $$\beta \beta $$ β β decay with emission of two neutrinos or Majorons in $$^{76}$$ 76 Ge from GERDA Phase I

Agostini¹,

Allardt²,

Bakalyarov³

et al. 2015

Eur. Phys. J. C

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“…Ref. [18]) up to the point near the outer surface where the Li concentration becomes high enough to result in a significant recombination probability. Due to the slow nature of the diffusion compared to the charge carrier drift in the active volume, the rise time of signals from interactions in this region is increased.…”

Section: Bege Detectorsmentioning

confidence: 99%

Pulse shape discrimination for Gerda Phase I data

et al. 2013

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The GERDA experiment located at the Laboratori Nazionali del Gran Sasso of INFN searches for neutrinoless double beta (0νββ) decay of 76 Ge using germanium diodes as source and detector. In Phase I of the experiment eight semi-coaxial and five BEGe type detectors have been deployed. The latter type is used in this field of research for the first time. All detectors are made from material with enriched 76 Ge fraction. The experimental sensitivity can be improved by analyzing the pulse shape of the detector signals with the aim to reject background events. This Page 2 of 17 Eur. Phys. J. C (2013) 73:2583 paper documents the algorithms developed before the data of Phase I were unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV γ rays from 208 Tl decays as well as two-neutrino double beta (2νββ) decays of 76 Ge are used as proxies for 0νββ decay.For BEGe detectors the chosen selection is based on a single pulse shape parameter. It accepts 0.92 ± 0.02 of signal-like events while about 80 % of the background events at Q ββ = 2039 keV are rejected.For semi-coaxial detectors three analyses are developed. The one based on an artificial neural network is used for the search of 0νββ decay. It retains 90 % of DEP events and rejects about half of the events around Q ββ . The 2νββ events have an efficiency of 0.85±0.02 and the one for 0νββ decays is estimated to be 0.90 +0.05 −0.09 . A second analysis uses a likelihood approach trained on Compton edge events. The third approach uses two pulse shape parameters. The latter two methods confirm the classification of the neural network since about 90 % of the data events rejected by the neural network are also removed by both of them. In general, the selection efficiency extracted from DEP events agrees well with those determined from Compton edge events or from 2νββ decays.

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“…The contribution from 42 K decays on the n + surface, on the other hand, is enhanced with respect to the coaxial detectors due to the thinner dead layer and has to be taken into account for the model. The n + surface dead layer is partially active [32], which in particular affects the detection efficiency for surface β interactions. Thus, the MC simulation used for 42 K on n + surface included an approximation of this effect.…”

Section: Background Model For Bege Detectorsmentioning

confidence: 99%

The background in the $$0\nu \beta \beta $$ 0 ν β β experiment Gerda

et al. 2014

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The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double beta (0νββ) decay of 76 Ge. The signature of the signal is a monoenergetic peak at 2039 keV, the Q ββ value of the decay. To avoid bias in the signal search, the present analysis does not consider all those events, that fall in a 40 keV wide region centered around Q ββ . The main parameters needed for the 0νββ analysis are described. A background model was devel- oped to describe the observed energy spectrum. The model contains several contributions, that are expected on the basis of material screening or that are established by the observation of characteristic structures in the energy spectrum. The model predicts a flat energy spectrum for the blinding window around Q ββ with a background index ranging from 17.6 to 23.8 × 10 −3 cts/(keV kg yr). A part of the data not considered before has been used to test if the predictions of the background model are consistent. The observed number of events in this energy region is consistent with the background model. The background at Q ββ is dominated by close sources, mainly due to 42 K, 214 Bi, 228 Th, 60 Co and α emitting isotopes from the 226 Ra decay chain. The individual fractions depend on the assumed locations of the contaminants. It is shown, that after removal of the known γ peaks, the energy spectrum can be fitted in an energy range of 200 keV around Q ββ with a constant background. This gives a background index consistent with the full model and uncertainties of the same size.

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Characteristics of signals originating near the lithium-diffused N+ contact of high purity germanium p-type point contact detectors

Cited by 56 publications

References 32 publications

Results on $$\beta \beta $$ β β decay with emission of two neutrinos or Majorons in $$^{76}$$ 76 Ge from GERDA Phase I

Results on $$\beta \beta $$ β β decay with emission of two neutrinos or Majorons in $$^{76}$$ 76 Ge from GERDA Phase I

Pulse shape discrimination for Gerda Phase I data

The background in the $$0\nu \beta \beta $$ 0 ν β β experiment Gerda

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